bio1012020-200303163958.pdf

DEPARTMENT OF BIOLOGICAL SCIENCES,
ADMIRALTY UNIVERSITY OF NIGERIA, DELTA-NIGERIA.
BIO 101: GENERAL BIOLOGY I (PART 1)
BY
MUSA, SAHEED IBRAHIM
B.Sc. Hons (Saudi), M.Sc. (Unilag), *PhD. (Uniben).
@Danzyy2 Musasa39id@gmail.com

COURSE DESCRIPTION AND OUTLINE:
COURSE DESCRIPTION: This course is a 3 credit unit course that aims to expose
students to the generalized basic forms of life sciences as regards lower organisms,
Plant and Animal Kingdom.
Topical Outlines:
 Course introduction
 Characteristics and classification of living things
 Generalized survey of Plants and Animals
 Cell history and Basic cell types
 Prokaryotic and Eukaryotic cells
 Cell structure and Organizations
 Cell growth and cell division (Mitosis and Meiosis)
 Basic Reproduction.
 Genetics and Heredity
 Ecology
 Evolution
 Animals and Plants: Lower and Higher
 Revision exercise/Continuous assessment test.

COURSE DESCRIPTION AND OUTLINE:
ATTENDANCE POLICY: All students must have atleast 75%
attendance to sit for the exam.
GRADING SYSTEM FOR THE COURSE: The course grading system is as
follows:
1. Assignments 10%
2. Test 30%
3. Final Examination 60%
TOTAL 100%.
Previous performance: Total 86
A: 17
B: 22
C: 30
D: 12
F: 5

Introduction
Universe:
 Stars
 Galaxies
 Asteroids
 Planets :
Earth

Introduction
 The first forms of life on Earth are thought to have
been microorganisms such as Cyanobacteria
 Existed Billion years in the Ocean
before Plants and Animals.
 Higher organisms such as birds are all relatively
recent, originating 130 to 200 million years ago.

Introduction
 Humans have inhabited this planet for only the last
2.5 million years, and only in the last 200,000 years
have humans started looking like we do today.
Ask EVOLUTION!

Introduction
Since the creation of modern day
Human, Man has continued to
search for knowledge about life.
 Employing different strategies that leads to a broad
field known as
BIOLOGY!

WHAT IS BIOLOGY
 Two Greek words:
BIOS meaning LIFE
LOGOS meaning STUDY
 Biology is the study of living organisms and their interactions with
one another and their environments.
 Science of Life.
 It is very broad and vast
 Biologists may study anything from the microscopic structures such
as bacteria or DNA or submicroscopic view of a cell to ecosystems
and the whole living planet.

WHAT IS BIOLOGY
Cure to HIV,
Alzheimer disease,
Cancer,
Paternal Mito. DNA
Genetic improvement
of Plants.
GMOs
Biological cleanings
Biological weapons
Biodiversity.

WHAT IS BIOLOGY
 Biological knowledge is tentative and refutable, therefore subject to
changes.
 Although, there are some basic principles of biology that should
hopefully remain useful for many years to come
 Most biological study is built on the foundations of five universally
recognized truths. These are:
1. Cells are the basic unit of life.
2. Genes are the basic units for passing traits from parent to offspring.
3. Evolution by natural selection is the process that has led to the great diversity of
species on Earth.
4. Living things maintain the environment within their cells and bodies.
5. Living things have the ability to acquire and transform energy.

WHAT IS BIOLOGY
 Biology is a massive field of study
 It is constantly developing as biologists around the world are
completing research and taking our understanding of life to new
levels.
 Every minute, new research are published in different fields of
biology and it is near on impossible for one person to keep up-to-date
with every topic related to biology.
 However, everyone has to start somewhere and studying biology can
enlighten your understanding of the world around you.
 Biology in the 21st century has moved from just studying it but
applying its knowledge in solving various problems.
 Therefore it is important to train the future biologist how researches
are conducted in this field to equip them for future discoveries.

Scientific methods of investigations:
 Science (from the Latin scientia, meaning “knowledge”)
 It is the knowledge that covers general truths or the operation of
general laws, especially when acquired and tested by the scientific
method.
 Scientific method is a method of research with defined steps that
include experiments and careful observation.
 Biologists study the living world by posing questions about it and
seeking science-based responses.
 This approach is common to other sciences as well and is often
referred to as the scientific method.

 First documented by England’s Sir Francis Bacon (1561–1626).
 Followed Inductive methods for scientific
inquiry.
 The scientific method is not exclusively
used by biologists but can be applied to
almost all fields of study as a logical,
rational problem-solving method.

1. Observation (often a problem to be solved)
2. A question: this deals with asking oneself why?
3. Proposing a Hypothesis: Recall that a hypothesis is a suggested
explanation that can be tested.
4. Testing a Hypothesis(Experimentation):
A valid hypothesis must be testable.
It should also be falsifiable.
It involves variables and controls
Involves treatments and replicates
Involves statistical analysis
5. Results and Discussion
6. Conclusion

Study of Life
 Biology is the study of life and therefore deals with everything about
life.
 All things that live are known in biology as organisms.
 Meaning they undergo the characteristics of life
 They range from higher, lower, microscopic and viruses

Study of Life
 In studying life, you study their basic units which are CELLs
 Cells can either be Prokaryotic or Eukaryotic based on the
development of the cell.
 They control all life activities in all organisms

Study of Life
 All cells is embedded with nucleus that controls vital activities of the
cell, including heredity through the GENE.
 Genes are the basic unit for heredity.
 They contain all the information required
to keep an organism alive.
 Found attached on a double helix
Stranded structure called DNA.
 Genes are the reason why children look
similar to their parents.

Study of Life
 Gene inheritance is always influenced by the environment
 This leads to gradual changes in organisms over a Billion years
 This is known as EVOLUTION.
 The process of evolution is visible in all aspects of life.
 Obvious similarities in structure and function of different species are
hard to ignore and the collection of evidence supporting the theory of
evolution has become undeniable

Study of Life
 Naturally, all organisms tries to adapt to its environment by
mentioning proper balance.
 In Homeotherms, this is known as Homeostasis

Fields of Biology:
 Zoology Marine Biology
 Botany Hydrobiology
 Cell Biology (Cytology) Biometrics
 Genetics OMICs
 Toxicology Biotechnology
 Biochemistry Oncology
 Forensic Biology Cardiology
 Molecular Biology Morphology
 Microbiology Histology (Tissues)
 Environmental Biology Embryology
 Physiology Evolution
 Anatomy Virology

CHARACTERISTICS OF LIVING ORGANISMS
 Are all activities displayed by organisms that made them to be
referred to as living.
 This means all other things that cannot do any of these activities are
non-living.
 There are seven activities which make organisms different from non-
living things.
 These characteristics are as follows:
1. NUTRITION 2. RESPIRATION
3. MOVEMENT 4. EXCRETION
5. GROWTH 6. REPRODUCTION
7. SENSITIVITY

1. NUTRITION:
 All living things take in materials from their surroundings that they
use for growth, metabolism and repair of worn out cells or to provide
energy.
 Nutrition is the process by which organisms obtain energy and raw
materials from nutrients such as proteins, carbohydrates and fats.
 Nutrition involves different stages which are ingestion, digestion,
absorption, transportation, assimilation and excretion.
 Different organisms have different modes of nutrition:
Autotrophic nutrition and
Heterotrophic nutrition.
.

1. NUTRITION:
 Autotrophic organisms make their food through the process of
photosynthesis. Otherwise the PRODUCERS
 Heterotrophic organisms cannot make their food but depend on the
food reserved by producers and feed on them. They have the ability to
break this food into simpler forms by the help of certain catabolic
enzymes.

1. NUTRITION:
Heterotrophic organisms can either be :
1. Parasitic, meaning they live inside or outside another organism called
the host and obtain food from them. E. g. Plathyhelmenthis
2. Saprophytic organisms derive food from dead organisms by releasing
substance that helps break complex food into simple forms. Eg.
bacteria, fungi, mold, yeast.
3. Holozoic feeding, complex organic substances are ingested (taken in)
without being broken down into smaller parts. After the intake such
foods are digested by internal enzymes. Examples are Human beings

2. RESPIRATION: Is the release of energy from complex food
substances in all living cells. Living things break down food within their
cells to release energy.
Respiration can either be CELLULAR respiration or PHYSIOLOGICAL
respiration.

2. RESPIRATION:
 All organisms take in food either in simpler or complex forms
 But for this food to be utilized by the organism there is need for it to
be further broken down into in series of steps to release energy to be
used for metabolic processes.
 It can be cellular respiration which nutrients are converted to energy
(ATP) with the help of certain enzymes or
 Physiological respiration which deals with transfer of oxygen and
carbon dioxide between cells and the external environment.

3. MOVEMENT: Is the ability of an organism to change position.
 It is otherwise known as LOCOMOTION
 Movement is for :
Food,
Mating pair
Escape from danger
Favorable shelter.
 Different organisms move in different ways, in some organisms such
as mammals, the movement is so obvious with the help of their upper
and lower limbs.
 While for organisms such as plants, the movement may be less
obvious through their roots. Some organism such as Paramecium
move with the help of their cilia.

3. MOVEMENT:
 All animals move at some time in their lives. Some later stay as polyp
such as Coral reefs or medusa such as Jelly fish.
 Most animals run, swim, fly, crawl, galloping, slithering, leaping,
climbing, swinging with aid of limbs. The limbs are moved by
muscles which are attached to the skeleton. Though, not all organisms
need limb for movement.
 Snakes are limbless are move by a zig-zag locomotion
and griping the ground to move forward. The fastest
moving snake is Dendroaspis polylepis
(Black mamba) (30km/h).

3. MOVEMENT:
 Some lower organisms also move with the help of other structures
such as:
Flagella in Euglena and Chlymadomonas,
Cilia is Paramecium,
Pseudopodia in Amoeba
 Some invertebrate such as roundworm and flatworms may use
muscular contractions, while aquatic invertebrate such as squid and
octopus may use medusa like structure to pump water in and out of
their body.

4. EXCRETION: Is the process whereby living organisms get rid of
their internal waste to the external environment.
 As a result of the many chemical reactions occurring in cells, they
have to get rid of waste products (toxic) which might poison the cells.
 It helps organisms control osmotic pressure by balancing inorganic
ions and water and acid-base. This creates Homeostasis.
 These wastes are often of two types:
1. Metabolic wastes are produced as a result of chemical
processes of living cells and are eliminated to avoid harmful
elevation of body temperature.
2. Non-metabolic wastes occur as a result of excessive
ingestion of a product above the body requirement. They are
majorly indigestible products that are not usable by the
system.

4. EXCRETION:
 Excretory wastes can be in solid form, liquid, gasses and heat.
 Different organisms have different methods of waste removal using
specialized organs or structures. For example, mammals use
Alimentary canal, Kidney among others for their waste removal.
 However, lower organisms such as Nematodes uses excretory canals
located on both sides of the intestine.

5. GROWTH: Is the irreversible increase in size and mass of an
organism over time.
 It deals with mitotic cell division which translates in increasing the
organism size.
 Growth is measured in terms of biomass and all organisms have
specific size they are required to grow.
 If an organism reaches its required growth size, cell multiplication
slows down and the current size is maintained.

5. GROWTH:
 It can be measured in terms of:
Increase in length,
Increase in area or volume,
Increase in the number of cells.
 Growth requirements:
Nutrients
Water
Temperature (Heat)
Light
Growth substances (Hormones)

6. REPRODUCTION: Is the process by which organisms replicate
themselves.
 It maintains life and the driving force behind evolution, genetics and
heredity.
 It can be:
1. Sexual reproduction such as Mammals
2. Asexual reproduction such as bacteria

6. REPRODUCTION:
 It can also occur in different ways such as:
Hermaphroditism
Binary fission
Multiple fission
Fragmentation
Regeneration
Budding
Parthenogenesis, etc….

7. SENSITIVITY: Is the ability of an organism to respond to stimuli.
 Stimuli are environmental moves which organisms are expected to
respond to, such as light, temperature, water, gravity and chemical
substances.
 Sensitivity is in other term called irritability.
It can be:
1. Voluntary or
2. Involuntary

USING EARTHWORM AS A CASE STUDY
 Movement: Circular and longitudinal muscles
 Respiration: Breakdown food to produce energy
 Sensitivity: Light, Temperature, Touch and
Ph sensitive cells scattered in their outer skin.
 Growth: Increase body cells
 Reproduction: Hermaphrodites but cannot
self-fertilize and need to mate with another individual.
After mating, a cocoon containing the
fertilized eggs is deposited in the soil.
 Excretion: Nitrogenous waste from their
anus that is the last segment of their body.
 Nutrition: Manure, fungi,
microrganisms and decaying animals.

CLASSIFICATION OF ORGANISMS
 The use of the hierarchical classification system helps us to impose order and a
general plan on the diversity of living things. Scientists have always tried to
organize and classify the objects, including living organisms, around them.
 Classification can be defined as grouping organisms according to their structural
similarities. This means that organisms that share similar features are placed in one
group.
 These groups are arranged from the largest group of organisms to the smallest group
of organisms.
 The groups, from largest to smallest, are arranged as follows: kingdom, phylum
(plural phyla), class, order, family, genus (plural genera) and species.
 The species is the smallest group of organisms. As you go through the classification
hierarchy, you will see that scientists have used broader features to put organisms
into kingdoms, which are the largest groups of organisms.
 When you move down towards the species, which are the smallest groups of
organisms, features are becoming specific.
 In other words, two organisms that belong to the same species share more features
than those in the same kingdom but in different species.

Species: A group of organisms with similar
features, and these organisms are capable
of breeding and produce fertile offspring.
Classification hierarchy has many uses:
1. Helps scientists to sort organisms in
order.
2. Helps them to identify new organisms
by finding out which group they fit.
3. Makes it easier to study organisms when
they are sorted in groups.
4. Makes it easier in giving organisms
name
5. Provides a taxonomic relationship
through dendrogram.

 Each kingdom is further divided into smaller groups called phyla, based on a few
features that are shared by some organisms, till the last classification.
 There are two systems of classifications;
Natural: based on observable similarities such as morphological or
evolutionary similarities
Artificial: based on like organisms that can fly in one group etc. non-
evolutionary features.
Classes Humans Chimpanzee Horse Mango
Kingdom Animalia Animalia Animalia Plantae
Phylum/D Chordata Chordata Chordata Magnoliophyta
Class Mammalia Mammalia Mammalia Magnoliopsida
Order Primates Primates Perissodactyla Sapindales
Family Hominidae Hominidae Equidae Anacardiaceae
Subfamily Homininae Homininae Equidinae Anacardieae
Genus Homo Pan Equus Mangifera
Species H. Sapiens P
. troglodytes E. ferus M. indica

LECTURE 3: Introduction to Plants and Animals

INTRODUCTION TO PLANTS AND ANIMALS
PLANTS: Are living things made up of plant cells.
 They need air, water, soil, and sunlight to live.
 They are sessile however, their leaves move to catch the sun and their
roots move towards water.
 Their seeds can be carried by animals or blown by the wind.
 Over 270,000 species of plants have been identified and classified, but
scientists believe that there are millions more waiting to be
discovered.
 BOTANY is the study of plants
 Body parts include flowers, fruits,
roots, stems, seeds, nuts, stems, and leaves.

PLANTS:
 For easy identification, plants are basically classified into:

PLANTS:
There are two different types of trees:
1. Non-flowering trees such as
pines and redwoods.
2. Flowering tree such as Mango or
Orange.
 Most non-flowering tress are tall.
 The tallest trees in the world are the redwoods of California, which
can grow to be 379 ft (115.55 m) in height.

PLANTS: USES
 Forms the basic food staples, and this is just one reason why plants are
important.
 Major source of oxygen and maintain eco-balance
 Used as state and national emblems as well
 Provides animals with shelter, produce clothing material, medicines,
paper products,
 Reduce noise levels and wind speed
 Reduce water runoff and soil erosion.
 Coal is also produced from plant materials that were once alive.
 Economic use
 For aesthetic purposes
 Used in textiles, photography, language, humor, architecture and art,
images of plants are used often.

ANIMALS: Animals are multicellular eukaryotic organisms that
form the biological kingdom Animalia.
 Made up of Animal cells
 With few exceptions, animals consume organic material, breathe
oxygen, and are able to move.
 Reproduce mostly sexually and grow from a hollow sphere of
cells, the blastula, during embryonic development.
 Higher forms show elaborate sensory and neuro-motor systems.
 Over 15 million living animal species have been described—of
which around 1 million are insects—but it has been estimated
there are over 7 million animal species are yet to be discovered.
 Animals range in length from 8.5 millionths of a metre to 33.6
metres (110 ft).

ANIMALS:
 ZOOLOGY is the study of Animals
 Most animals are diploid organisms with haploid gametesmeaning that their
body (somatic) cells are diploid and haploid reproductive (gamete) cells are
produced through m except for bees
 Most animals undergo sexual reproduction: This fact distinguishes animals
from fungi, protists, and bacteria, where asexual reproduction is common or
exclusive. However, a few groups, such as cnidarians, flatworm, and
roundworms, undergo asexual reproduction, although nearly all of those
animals also have a sexual phase to their life cycle.
 Though different animals differ in their form and structure, there are some
fundamental similarities in them such as arrangement of cells, body
symmetry and nature of coelom, diploblastic or triploblastic nature of the
body wall, segmentation, presence or absence of notochord. These features
form the basis for the classification of animals.
 Animals are also classified into different level from simple to complex
known as level of organization.

ANIMALS:
 Levels of organization in Animals are:
 Cellular level of organization – e.g.:- Sponges.
 Tissue level of organization- e.g.:- Coelenterates.
 Organ system level of organization- e.g.:-Platyhelminthes and other higher
phyla.
 System level of organization- e.g: Reproductive system
 Organ level of organization: Man

ANIMALS:
 Are classified based on the type of symmetry of their body
plan:
Radially symmetrical such as Jellyfish and adult sea anemones.
Bilaterally symmetrical such as human body
Asymmetrical such as Amoeba.

ANIMALS:
 One of the unique character of Animals is Gastrulation.
 At this stage, some are :
Diploblast (Endoderm and Ectoderm) radially symmetry
Triploblast (Endoderm, Mesoderm and Ectoderm) bilateral
symmetry).

ANIMALS:
 From the mesoderm in Animals, organisms are classified to
be:
Coelomate: Have coelomic cavity (space filled with
fluid)
Acoelomate: Have no coelomic cavity
It houses many organs such as the digestive system,
kidneys, reproductive organs, and heart, and contains
the circulatory system.
Some can be Pseudoceolomate or Eucocoelomate

ANIMALS:
 Can broadly be classified into vertebrate and invertebrate
animals depending on the presence or absence of bony
structures such as cranium and vertebrae.
 The simplest of all the invertebrates are the Parazoans,
which include only the phylum Porifera: the sponges.
 Others are Phylum Cnidaria such as Hydra spp.
 Phylum Platyhelminthes such as flat worms,
 Phylum Nematoda such as roundworm,
 Phylum Molllusca such as Snail,
 Phylum Annnelida such as earthworms,
 Phylum Arthropoda such as insects and
 Phylum Echinodermata such as sea urchin.

ANIMALS:
 Vertebrate animals are among the most recognizable
organisms of the animal kingdom.
 More than 62,000 vertebrate species have been identified.
The vertebrate species now living represent only a small
portion of the vertebrates that have existed.
 These animals includes Fishes,
 Amphibians such as frogs,
 Reptiles such as lizards,
 Birds such as eagle and
 Mammals such as Man

ANIMALS: USES
 Ecological balance
 Economic importance such as silkworm belongs to the
phylum arthropoda of the animal kingdom.
 Nutritional importance
 Pollinators of important crops
 Food crops
 Biological researches
 Environmental cleanups

#IAmAndIWill
DidYouKnow:
 17 people die of cancer every minute
 There are over 200 types of cancer
 Common causes are Poor nutrition,
Smoking, Physical inactivity, Radiation,
Genetics.
 Most in men are Prostrate, lung and
Colorectal.
 Most in Breast, Lung and Colorectal
 Most in children, Leukemia, brain
Tumors and lymphoma.
 Symptoms: Lumps, bloody discharge

#IAmAndIWill
DidYouKnow:
Symptoms:
 Lumps, Bloody discharge from nipples.
Bladder changes, bowel changes,
Trouble swallowing, pain after eating,
Nausea, vomiting, fatigue, headaches,
Seizure, vision changes, unhealing sore,
Control:
Biopsy, surgery, green tea, acupuncture,
Healthy life style, nutriton and diet
Control.

CELLS: Brief history and types
 Cells are the basic and functional unit of life.
 The evolution of cell dates back to the history of Aristotle
(384 —322 B.C.), to Robert Hooks (1665-1703) to current
cellular discoveries.
 These cells are found in all living organisms and are the
making blocks of all organisms. There are different types of
cells based on different organisms and uniqueness
 Cells differ in size, form and function, degree of
specialization and average generation time.
 The biological science which deals with the study of
structure, function, molecular organization, growth,
reproduction and genetics of the cells, is called Cytology or
Cell Biology.

 Cells were first seen over 340 years ago.
 Ancient Greek philosophers such as Aristotle (384 —322 B.C.) and
Paracelsus concluded that “all animals and plants, however complicated, are
constituted of a few elements which are repeated in each of them.”
 Many centuries later, owing to the invention of magnifying lenses, the world
of microscopic dimensions was discovered.
 Da Vinci (1485) recommended the uses of lenses in viewing small objects.
 In 1558, Swiss biologist, ConradGesner (1516—1565) published results of
his studies on the structure of a group of protists called FORAMINIFERA.
 The first useful compound microscope was invented in 1590 by Francis
Janssen and Zacharias Janssen. Their microscope had two lenses and total
magnifying power between 10X and 30X. Such types of microscopes were
called “flea glasses”, since they were primarily used to examine small whole
organisms such as fleas and other insects.
 In 1610, an Italian Galileo Galilei (1564 —1642) invented a simple
microscope having only one magnifying lens. This microscope was used to
study the arrangement of the facets in the compound eye of insects.

 Robert Hooke, an English scientist examined a thin section of a cork in 1665 and
discovered that is composed numerous box-like structures which he named as cells.
 Antonie van Leeuwenhoek improved certain lenses, he then used the lenses in 1676
and observed wide variety of living unicellular organisms in drops of water and call
them “Animalcules”.
 In 1838, a German botanist called Matthias Schleiden proposed that all plant tissues
consist of cells.
 In 1839, his co-worker and a German Zoologist called Theodore Schwann used
Schleiden’s thesis to the animals and proposed that all animal tissues consist of cells.
 This implied a basic sameness of living things and laid the foundation for the
development CYTOLOGY
 By 1840s, it was recognized that cell is the basic unit of life. An idea that was first
expressed by Matthias Schleiden and Theodore Schwann in their cell theory of
1839.
 The German physiologist Rudolf Virchow showed in 1855 that cells are derived
from previously existing cells, and thus that a continuity exists between past and
present living things.
 Since then, the knowledge about cell has progressed a very long way, helped by the
developments in technology which have made ever increasing details available.

 Cell theory:
1. All living organisms (animals, plants and microbes) are
made up of one or more cells,
2. All metabolic reactions in unicellular and multicellular
organisms take place in cells,
3. Cells originate only from previously existing cells, that is
no cell can originate spontaneously or de novo, but comes into
being only by division and duplication of already existing cells
(Virchow, 1858).
4. Cell is the structural and functional unit of life.

 Biological organization is a hierarchy of structural levels: Classification of organism from the
simplest to the most complex molecular processes.
Atoms Molecules Organelles Cells Tissues Organs Organ
systems Multicellular Organism Population Community Ecosystem
Biosphere
Molecule: A group of small chemical units called atoms held together by chemical bonds
 Organelle: a membrane-bound structure that performs a specific function in a cell, and
 Cell: the fundamental structural and functional units of life
 Tissue: a group of similar cells that perform a specific function
 Organ: a structure that is composed of tissues and provides a specific function for the organism
 Organ system: several organs that participate in a specific function
 Organism: an individual living thing
 Population: interbreeding species living in a specific area at a time
 Community: the entire group of organisms of different populations living in an ecosystem
 Ecosystem: all the organisms living in a particular area and the physical components with 0which
they interact
 Biosphere: all of the environments on Earth that support life.

CELLS: Types
 Cells are classified into several types depending on structures, functions,
numbers and formations. Each cell is perfectly suited for the role it
performs.
 Based on structure, the cells are of two types: Prokaryotic and Eukaryotic
cells.
1. Prokaryotic Cells: This means in Greek term (pro = primitive or
before; karyon = nucleus).
 They are small, simple and most primitive cells.
 Probably the first to come into existence perhaps 3.5 billion years ago.
 Lacks membrane bound nucleus and therefore the nucleus is dispatched around
the cytoplasm.
 Lacks most cell organelles such as endoplasmic reticulum, Golgi apparatus and
mitochondria.
 Ribosomes, enzymes and food storage granules are found within the cytoplasm.
 Respiration takes place on special piece of plasma membrane called
MESOSOME.

CELLS: Types
 Genetic material is a single strand coiled-up in the center to
form nucleoid.
 A form of chlorophyll is found in photosynthetic prokaryotes.
 Bacteria and blue-green algae (Cyanobacteria) are examples
of prokaryotes.

CELLS: Types
2. Eukaryotic Cells: This means in Greek term (Gr., eu=good,
karyotic=nucleated) are essentially two envelope systems
 Are very much larger than prokaryotic cells.
 Has a definite nucleus and membrane bounded organelles
suspended in the cytoplasm.
 There is presence of minute filaments and tubules called
cytoskeleton .
 The eukaryotic cells are the true cells which occur in the
plants (from algae to angiosperms) and the animals.
 Believed to exist after the prokaryotic cells

CELLS: Types
 All the cells are typically composed of plasma membrane,
cytoplasm and its organelles, viz., mitochondria, endoplasmic
reticulum, ribosomes, Golgi apparatus, etc., and a true
nucleus. Here the nuclear contents, such as DNA, RNA,
genes and chromosomes are present.

CELLS: Types
 Cells can be classified based on number into:
1. Unicellular: These are organisms having one single cell.
are bacteria and blue-green algae and they belong to
kingdom Monera and Protista.
2. Multicellular: These are organisms having two or more
cells aggregated together forming an organism.
Examples are Animals and Plants.

CELLS: Types
 Cells can also be classified based on cellular activities such as
photosynthesis into:
1. Animal cells:
2. Plant cells

CELLS: Types
 Other forms of Animal cells are:
1. Stem Cells: Are unique cells of the body in that they are unspecialized
and have the ability to develop into specialized cells for specific organs
or to develop into tissues.
2. Bone Cells: Are a type of mineralized connective tissue and a major
component of the skeletal system. Bone cells form bone, which is
composed of a matrix of collagen and calcium phosphate minerals.
3. Blood Cells: From transporting oxygen throughout the body to fighting
infection, cells of the blood are vital to life. The three major types of
cells in the blood are red blood cells, white blood cells, and platelets.
Red blood cells determine blood type and are also responsible for
transporting oxygen to cells. White blood cells are immune system cells
that destroy pathogens and provide immunity. Platelets help to clot
blood and prevent excessive blood loss due to broken or damaged
blood vessels. Blood cells are produced by bone marrow.
4. Muscle cells: Form muscle tissue, which is important for bodily
movement. Muscles can be Skeletal muscles or Smooth muscles.

CELLS: Types
5. Fat cells: Also called adipocytes, are the major cell component of adipose
tissue. Adipocytes contain droplets of stored fat (triglycerides) that can be
used for energy. Adipose cells also have an endocrine function as they
produce hormones that influence sex hormone metabolism, blood pressure
regulation, insulin sensitivity, fat storage and use, blood clotting, and cell
signaling.
6. Skin cells: The skin is composed of a layer of epithelial tissue
(epidermis) that is supported by a layer of connective tissue (dermis) and an
underlying subcutaneous layer. The skin protects the internal structures of
the body from damage, prevents dehydration, acts as a barrier against
germs, stores fat, and produces vitamins and hormones.
7. Nerve cells: Neurons are the basic unit of the nervous system. Nerves
send signals among the brain, spinal cord, and other body organs via nerve
impulses. Endothelial cells: form the inner lining of cardiovascular
system and lymphatic system structures. These cells makes up the inner
layer of blood vessels, lymphatic vessels, and organs including the brain,
lungs, skin, and heart. Endothelial cells are responsible for angiogenesis or
the creation of new blood vessels. They also regulate the movement of
macromolecules, gases, and fluid between the blood and surrounding
tissues, and help to regulate blood pressure.

CELLS: Types
8. Pancreatic cells: Have endocrine function and secrete hormones.
They are found in small clusters called islets of Langerhans.
Hormones produced by these cells include insulin, glucagon, and
gastrin. Pancreatic cells are important for regulating blood glucose
concentration levels as well as for the digestion of proteins,
carbohydrates, and fats.
9. Cancer cells: results from the development of abnormal properties
in normal cells that enable them to divide uncontrollably and spread
to other locations. This can be caused by mutations that occur from
factors such as chemicals, radiation, chromosome replication errors,
or viral infection. Cancer cells lose sensitivity to anti-growth signals,
proliferate rapidly, and lose the ability to undergo apoptosis or
programmed cell death.

CELLS: Types
10. Sex cells: Gametes are reproductive cells produced in male
and female gonads. Male sex cells or sperm are motile and have a
long, tail-like projection called a flagellum. Female sex cells or ova
are non-motile and relatively large in comparison to the male
gamete.

CELLS: Types
 Other forms of Plant cells are:
1. Parenchyma cells: Are the majority of cells in a plant. They are
found in leaves and carry out photosynthesis and cellular respiration,
along with other metabolic processes. They also store substances like
starches and proteins and have a role in plant wound repair.
2. Collenchyma cells: Provide support to growing parts of a plant.
They are elongated, have thick cell walls, and can grow and change
shape as a plant grows.
3. Sclerenchyma cells: Are hard cells that are the main supporting
cells in the areas of a plant that have ceased growing. Sclerenchyma
cells are dead and have very thick cell walls.
4. Xylem cells: Transport mostly water and a few nutrients
throughout a plant, from the roots to the stem and leaves.
5. Phloem cells: Transport nutrients made during photosynthesis to
all parts of a plant. They transport sap, which is a watery solution
high in sugars.

CELLS: Types
 Other forms of Plant cells are:

LECTURE 5: Prokaryotic and Eukaryotic

CELLS: PROKARYOTIC AND EUKARYOTIC
 The terms prokaryotic and eukaryotic were suggested by Hans Ris in the
1960’s.
PROKARYOTIC CELLS:
 Are small, simple and most primitive type of cell.
 The first to come into existence perhaps 3.5 billion years ago.
 Known to be the cells of bacteria, cyanobacteria and blue green algae.
 Are essentially a one-envelope system organized in depth.
 It consists of central nuclear components (viz., DNA molecule, RNA
molecules and nuclear proteins) surrounded by cytoplasmic ground
substance, with the whole enveloped by a plasma membrane.
 The cytoplasm lacks in well-defined cytoplasmic organelles such as
endoplasmic reticulum, Golgi apparatus, mitochondria and centrioles.
 Generally, prokaryotic cells are distinguished from the eukaryotic cells
primarily on the basis of what they lack such as a nuclear envelope (Nuclear
membrane) and some other cytoplasmic membrane.

CELLS: PROKARYOTIC AND EUKARYOTIC
 They also do not contain nucleoli, cytoskeleton (microfilaments
and microtubules), centrioles and basal bodies.
 One of the most known examples is bacteria. Some scientists use
the word prokaryotic cell and bacteria interchangeably.

PROKARYOTIC CELLS
Bacteria (bacterium):
 Are amongst the smallest organisms.
 Most primitive, simple, unicellular, prokaryotic and microscopic organisms.
 Belong to the Kingdom Monera.
 All bacteria are structurally relatively homogeneous, but their biochemical activities and the
ecological niches for which their metabolic specialisms equip them, are extremely diverse.
 Found almost everywhere
 Bacteria (Thermophiles) thrive well in any temperature
 They occur in vast numbers
 They have pilli which helps them in conjugation
 They multiply at a very fast rate
 Examples are cyanobacteria and Nitrosomonas

PROKARYOTIC CELLS
1. They exist in different sizes (0.15 to 0.3μm and 13 to 15μm in length).
2. Forms (Cocci, Bacilli, Spirilla, Vibrios).
3. Cell wall staining

PROKARYOTIC CELLS
1. SIZE: Typically, a bacteria ranges between 1μm (one micrometre) to 3 μm.
 They are barely visible under the light microscope.
 The smallest bacteria cell is Dialister pneumosintes (0.15 to 0.3μm in length).
 The largest bacteria cell is Spirillum volutans (13 to 15μm in length).

PROKARYOTIC CELLS
2. SHAPES AND FORMS: COCCI (coccus)
 Spherical, oval or round in shape
 The shape is determined by the cell wall of the organism and therefore varies from
one type of cocci bacteria to another
 These bacterial cells may occur singly micrococci, or attached.
 The attachment may be in :
 Diplococci (2 Pairs) e.g., Pneumonia causing bacterium, (Diplococcus pneumoniae)
and boil causing bacterium Staphylococcus aureus.

PROKARYOTIC CELLS
2. SHAPES AND FORMS: COCCI (coccus)

PROKARYOTIC CELLS
2. SHAPES AND FORMS: BACILLI (bacillus):
 These are rod-like bacteria.
 They generally occur singly, but may occasionally be found in attached in pairs
(diplobacilli) or other conformations
 They form endospores and are facultative anaerobes.
 Cause certain most notorious diseases of man such as tuberculosis (Bacillus
tuberculosis), tetanus (Clostridium tetani), typhoid (Salmonella or Bacillus
typhosus) among others.

PROKARYOTIC CELLS
2. SHAPES AND FORMS: SPIRILLA (spirillum).
 These are also called spirochetes.
 Have spiral-shaped and are motile bacteria.
 Also have helical shape and are flexible
 They have been shown to produce mycelium
 They use filaments for movement
 Spirilla cause human disease such as syphilis (Treponema pallidum).

PROKARYOTIC CELLS
 2. SHAPES AND FORMS: VIBRIOS (Vibrio).
 These are comma-shaped or bent-rod like bacteria
 Cause human disease such as cholera (Vibrio cholerae).
 Others are Vibrio mytili, Vibrio anguillarum and Vibrio
oarahaemolyticus.

PROKARYOTIC CELLS
 3. CELL WALL STAINING:
 On the basis, bacteria are grouped into: Gram positive and Gram negative
bacteria
 The method is named after Christian Gram who developed it in Denmark in 1884

EUKARYOTIC CELLS
 Have true nucleus.
 They are essentially two envelope systems and they are very much
larger than prokaryotic cells.
 Are the cells which occur in the plants and the animals.
 They are well developed and have all cell organelles needed for
specific metabolic activities.
 Though the eukaryotic cells have different shape, size, and
physiology; all the cells are typically composed of plasma membrane,
cytoplasm and its organelles such as mitochondria, endoplasmic
reticulum, ribosomes, Golgi apparatus and a true nucleus.
 In these cells, the nuclear contents, such as DNA, RNA,
nucleoproteins and nucleolus remain separated from the cytoplasm by
the thin, perforated nuclear membranes.
 The cells also vary in ways such as:

EUKARYOTIC CELLS
1. Cell Shape:
 The basic shape of the eukaryotic cell is Spherical; however, the shape is
ultimately determined by the specific function of the cell. Thus, the shape of
the cell may be variable (i.e., frequently changing the shape) or fixed.
 Variable or irregular shape occurs in Amoeba and white blood cells or
leucocytes.
 Fixed shape of the cell occurs in almost all protists (e.g., Euglena,
Paramecium), plants and animals.
 In unicellular organisms the cell shape is maintained by tough plasma
membrane and exoskeleton.
 In a multicellular organism, the shape of the cell depends mainly on its
functional adaptations and partly on the surface tension, viscosity of the
protoplasm, cytoskeleton of microtubules, microfilaments and intermediate
filaments, the mechanical action exerted by adjoining cells and rigidity of
the plasma membrane (i.e., presence of rigid cell wall in plant cells).

EUKARYOTIC CELLS
1. Cell Shape:
 The shape of the cell may vary from animal to animal and from organ
to organ.
 Even the cells of the same organ may display variations in the shape.
Thus, cells may have diverse shapes such as polyhedral (with 8, 12 or
14 sides; e.g., squamous epithelium); flattened (e.g., squamous
epithelium, endothelium and the upper layers of the epidermis);
cuboidal (e.g., in thyroid gland follicles); columnar (e.g., the cells
lining the intestine); discoidal (e.g., red blood cells or erythrocytes);
spherical (e.g., eggs of many animals); spindle shaped (e.g., smooth-
muscle fibres); elongated (e.g., nerve cells or neurons); or branched
(e.g., chromatophores or pigment cells of skin).
 Among plants, the cell shape also depends upon the function of the
cell.
 For example, cells such as glandular hairs on a leaf, the guard cells of
stomata and root hair cells have their special shape.

EUKARYOTIC CELLS
2. Cell Size:
 The eukaryotic cells are typically larger (mostly ranging between 10
to 100 μm) than the prokaryotic cells (mostly ranging between 1 to 10
μm).
 Size of the cells of the unicellular organisms is larger than a typical
multicellular organism’s cells. For example, Amoeba proteus is
biggest among the unicellular organisms; its length being 1 mm (1000
μm).
 One species of Euglena is found up to 500 μm (0.5 mm) in length.
 Diatoms have a length of 200 μm or more.
 The single-celled algae, Acetabularia spp which consists of a stalk
and a cap is exceptionally large-sized and measures up to 10 cm in
height.
 The size of the cells of multicellular organisms ranges between 20 to
30 μm.

EUKARYOTIC CELLS
2. Cell Size:
 Among animals, the smallest cells have a diameter of 4 μm (e.g.,
polocytes); human erythrocytes being 7 to 8 μm in diameter.
 Largest animal cell is the egg of ostrich, having a diameter of 18 cm
(its yolk or deutoplasm is about 5 cm in diameter); though, some
nerve cells of human beings have a meter long “tails” or axons.
 Among the multicellular plants, the largest cell is the ovule of Cycas.
 The fibre cells (i.e., sclerenchyma cells) of Manila hemp are over 100
cm in Length.

EUKARYOTIC CELLS
3. Cell Volume:
 The volume of a cell is fairly constant for a particular cell type and is
independent of the size of the organism. (This is called the law of
constant volume).
 For example, kidney or liver cells are about the same size in the bull,
horse and mouse. The difference in the total mass of the organ or
organism depends on the number, not on the volume of the cells.
 Thus, the cells of an elephant are not necessarily larger than those of
other tiny animals or plants.
 The large size of the elephant is due to the larger number of cells
present in its body.

EUKARYOTIC CELLS
4. Cell Number:
 The number of cells present in an organism varies from a single cell in
a unicellular organism (Protists such as protozoa and protophyta) to
many cells in multicellular organisms (Most plants, fungi and
animals).
 The number of cells in the multicellular organisms usually remains
correlated with size of the organisms and, therefore, small-sized
organism has less number of cells in comparison to large sized
organisms. For example, a human being weighing about 80 kg may
contain about 60 thousand billion cells in his body. This number
would be more in certain other multicellular organisms.
 Further, the number of cells in most multicellular organisms is
indefinite, but the number of cells may be fixed in some multicellular
organisms. For example, in rotifers, number of nuclei in the various
organs are found to be constant in any given species.
 This phenomenon of cells or nuclear constancy is called eutely.

EUKARYOTIC CELLS
5. Cell Structure:
An eukaryotic cell consists of the following components:
A. Plasma membrane or Cell membrane.
B. Cytoplasm and
C. Nucleus.
A. Plasma membrane: Every kind of cell is bounded by a living, extremely
thin and delicate membrane called plasma membrane or cell membrane.
 In plant cells, plasma membrane occurs just inner to cell wall, bounding the
cytoplasm.
 The plasma membrane is a selectively permeable membrane; its main
function is to control selectively the entrance and exit of materials.
 This allows the cell to maintain a constant internal environment
(homeostasis).
 Transport of small molecules such as water, oxygen, carbon dioxide,
ethanol, ions and glucose across the plasma membrane takes place by
various means such as osmosis, diffusion and active transport.

EUKARYOTIC CELLS
B. Cytoplasm: The plasma membrane is followed by the cytoplasm
which is distinguished into Cytosol which is the aqueous portion of the
cytoplasm (the extranuclear protoplasm) and of the nucleoplasm (the
nuclear protoplasm), the Cytoplasmic structures which contains the
cytoplasmic organelles without the nucleus.
 Some livings as well as non-living substances are also found here.
 Cytoskeleton are also found here which gives shape and balance to the
cell as also helps in transfer of metabolic substances within the cell.
C. Nucleus: The nucleus is centrally located and spherical cellular
component which controls all the vital activities of the cytoplasm and
carries the hereditary material the DNA in it.
 The nucleus is like a brain of the cell.
 It is being covered by a protective nuclear membrane in eukaryotic
cells.

EUKARYOTIC CELLS
S/N Feature Prokaryotic Cells Eukaryotic Cells
1 Size Mostly 1 – 10 μm Mostly 10- 100 μm
2 Multicellular forms Rare Common with extensive tissue formation
3 Cell wall Present but not in all Present in plant and fungal cells only
4 Plasma membrane Present Present
5 Nucleus Absent Present
6 Nuclear membranes Absent Present
7 Chromatin with
histone
Absent Present
8 Genetic material Circular or linear,
double-stranded DNA.
Genes are not
interrupted by intron.
Linear double-stranded DNA. Genes
frequently interrupted by intron
sequences, especially in higher
eukaryotes.
9 Nucleoid and
mitotic apparatus
Absent Present
10 Plasmids Commonly present Rare
11 Mitochondria Absent Present
12 Endoplasmic
reticulum
Absent Present
13 Vacoules Absent Present
14 Lysosomes Absent Present
15 Chloroplasts Absent Present (only in plants)
16 Centrioles Absent Present (absent in higher plants)
17 Ribosomes Present Present
18 Microtubules Absent Present
19 Metabolic patterns Great variations Share cytochrome electron transport chain
20 Sexual system Rare Both sexes involve in sexual participation.

LECTURE 6: Cell Structure and Organization

CELL STRUCTURE
Animal Cell:
 This is a type of cell found in all organisms in the kingdom Animalia.
 Some members of kingdom fungi may also have this type of cell
 This cell lacks a chloroplast and therefore do not undergo
photosynthesis
 It is surrounded by a thin layer called plasma membrane (Cell
membrane)
 The surrounded portion is called protoplasm, which consist of
cytoplasm and a nucleus
 The cytoplasm consists of numerous organelles such as Golgi
apparatus, Mitochondria, Endoplasmic reticulum, Lysosome and
Centriole.

CELL STRUCTURE
Animal Cell:
 Food materials and other granules are also present in the cytoplasm
 In the cytoplasm, complex chemical reactions take place for the supply of energy
and building up of materials for cell activities
 While nucleus is bounded by nuclear membrane, it contains the nucleolus and
small chromatin granules where chromosomes developed.

CELL STRUCTURE
Plant Cell:
 This is a type of cell found in all organisms in the kingdom Plantae
 This cell has chloroplast (the green pigment) which gives it the ability to photosynthesize
 In addition to features plant cell shares in common with animal cell, plant cell is surrounded
by a thick layer made up of cellulose upon which is called the cellulose cell wall.
 The cell wall is being interrupted at intervals by narrow pores called plasmodesmata
 Plastid which is spherical in shape is found in cytoplasm of plant cell. These plastids are of
two types: leucoplast which contains starch and chloroplast which contains chlorophyll that
gives the green pigment.

CELL ORGANELLS AND FUNCTIONS:
1. CELL WALL
 Tough cellulose tissue that surrounds plant cells, bacteria cells, fungi cells and some
archaea.
 It is absence in Animal cells
 It is located outside the cell membrane
 It is made up of cellulose (Lignin, pectin, tannin and suberin.

1. CELL WALL
Functions:
 It gives protection to the inner contents
 It is free permeable structure that allows water, oxygen and carbon-dioxide to pass in and out
of cell using apoplastic pathways
 They exchange communication between adjacent cells through a narrow thread that passes
through the cell wall called Plasmodesmata.

2. PLASMA MEMBRANE (Cell membrabe):
 It is the outer layer that surrounded the animal cell
 In plant cell, it is found just after the cell wall
 It is flexible and selectively permeable membrane
 It is made up of mainly proteins and lipids
 It is found in plants, animals and protozoa

2. PLASMA MEMBRANE (Cell membrabe):
Functions: Serves as barrier between cell and its environment and provides protection
 The cell membrane physically separates the intracellular components (e.g. organelles in
eukaryotic cells) from the extracellular environment.
 It controls movement of materials in and out of the cell
 It maintains homeostasis
 It synthesizes and assemble cell wall
components in plants
 In many cases, the cell membrane
also helps to hold the cytoskeleton.

3. CYTOSKELETON:
 This is a system of protein filaments in the cytoplasm of a eukaryotic
cell that gives the cell shape and the capacity for directed movement.
 Its most abundant components are microfilaments, microtubules, and
intermediate filaments.

3. CYTOSKELETON:
 Functions:
 Gives cell shape
 Allow movement of metabolic materials within the cell.

4. CYTOPLASM:
 Houses all the contents within the cell membrane
 It includes the cytosol (i.e. the semi-fluid part of a cell's cytoplasm) as well as the
cell organelles
 Also houses cytoskeleton
 It consists mainly of water and contains enzymes,
salts, organelles, and various organic molecules
 Cytoplasm plus a nucleus is called protoplasm.

CELL GROWTH AND CELL DIVISION:
 Growth is an increase in size or mass of a developing/ living system
 It is an irreversible process that occur at all organizational levels.
 Cell growth is an increase in size or mass of a cell. It is multifactorial
 Growth embodies following three interacting growth patterns:
(1) Auxetic growth, which is an increase in cell mass or auxesis
(2) Multiplicative growth, which is an increase in cell number due to cell division; and
(3) Accretionary growth, which is the growth due to accumulation of extracellular
products
Generally, when rate of anabolism (i.e., photosynthesis, protein synthesis, etc.) far
exceeds the rate of catabolism (i.e., respiration), the growth of protoplasm (i.e., auxetic
growth) takes place.

4. CYTOPLASM:
Functions:
 Helps to move materials around the cell and also dissolves cellular waste.
 Houses the cell organelles.

5. VACOULE:
 Found only in plant cell
 It can occupy a large proportion of the total volume of the cell (70%)
 Enclosed by a vacuolar membrane called the tonoplast
 Content of the vacuole is cell sap, which is a solution of salts, sugars and organic
acids
 Contain enzymes needed for recycling
components of cells, e.g. chloroplasts.

5. VACOULE:
Functions:
 It maintains turgor pressure (turgidity) inside the cell. This pressure pushes the
plasma membrane against the cell wall. Plants need turgidity to maintain rigidity

6. MITOCHONDRIA:
 Power house of the cell
 Coined in 1898 by Alvert von kolliker and Carl benda
 Found in both plant and animal cells
 Have a sausage shape and have Cristae
 The mitochondria matrix contains lipids, proteins, circular DNA
molecule (mtDNA) and 55S ribosomes (mitoribosomes)
 It can synthesize 10% of their proteins
 Center for cellular respiration and energy production

6. MITOCHONDRIA:
Functions: Breakdown sugar molecules to produce energy in form of Adenosine
triphosphate (ATP).
 Contain enzyme systems needed to synthesize (ATP) by oxidative
phosphorylation.
 Control the level of water and other materials in cell.
 Recycle and decompose proteins, fats and carbohydrates

Cellular Respiration:
 Production of ATP in mitochondria, using fuel molecules and molecular
oxygen (O2) is called cellular respiration
 It is a catabolic process involving redox reaction
 Nutrients commonly used by plants and animal cells in respiration include
sugar, amino acids and fatty acids and a molecular oxygen (O2)
 Organisms that use oxygen as a final electron acceptor in respiration are
described as aerobic, while those that do not are referred to as anaerobic
 The energy stored in ATP can then be used to drive processes requiring
energy, including biosynthesis, locomotion or transportation of molecules
across cell membranes.

Cellular Respiration:
The product of this process is energy in the form of ATP (Adenosine
triphosphate), substrate-level phosphorylation, NADH and FADH2.
 Simplified reaction: C6H12O6 (aq) + 6O2 (g)----------------6CO2 (g) +
6H2O (l)
 ΔG = - 2880 kJ per mole of C6H12O6
 The negative ΔG indicates that the reaction can happen
spontaneously.

7. CHLOROPLASTS:
 Sites of photosynthesis within plant cells
 They have grana which is the main functional unit of the chloroplast
 Stroma contains a variety of photosynthetic enzymes.

7. CHLOROPLASTS:
Functions:
 They are the center for photosynthesis.
 They aid in production of glucose and oxygen as bye-product

Photosynthesis: Energy in sunlight is converted into chemical energy. Photosynthesis
in plants takes place in the chloroplasts. Photosynthesis takes place in three stages:
 1. Capturing energy from sunlight;
 2. Using the energy to make ATP and reducing power in the form of a
compound called NADPH; and
 3. Using the ATP and NADPH to power the synthesis of organic molecules
from CO2 in the air (carbon fixation).
 The first two stages take place in the presence of light and are commonly called the
light reactions.
 The third stage, the formation of organic molecules from atmospheric CO2, is called
the Calvin cycle. As long as ATP and NADPH are available, the Calvin cycle may
occur in the absence of light.

Factors affecting photosynthesis:

8. GOLGI APPARATUS:
 This is a stack of parallel, flattened membrane pockets
 They linked with but are not joined to the rough endoplasmic reticulum
 They resembled rough endoplasmic reticulum without ribosomes and are usually
found near nucleus
 Golgi apparatus was discovered by Camillo Golgi in 1898.

8. GOLGI APPARATUS:
Functions:
 They are responsible for the production and secretions such as plate and cell wall
materials.
 They serve as protein packaging plants.
 They regulate water.

9. LYSOSOMES:
 These are rod-shaped or spherical structures surrounded by a unit membrane boundary that
contain a powerful mix of digestive enzymes
 They frequently fuse with each other and with membrane bound vacuoles containing either
food or an obsolete organelle.

9. LYSOSOMES:
Function:
 They transport the undigested materials to cell membrane for removal.
 They serve as digestive plant for proteins, lipids and carbohydrates into smaller molecules.
 They digest old cell parts and can destroy themselves if the entire cell is damage or running
down. Apoptosis or Necrosis.

10. RIBOSOMES:
 These are small round bodies found free or attached to
endoplasmic reticulum, making the Rough endoplasmic
reticulum
 They compose 25% of cell’s mass
 Each cell contains thousands of ribosomes
 Ribosomes were discovered by cell biologist George Palade

10. RIBOSOMES:
Functions:
 They play important role in the protein synthesis
 Mobile ribosome injects proteins directly into cytoplasm.

11. NUCLEUS:
 This is the brain of the cell
 It is the largest and most important cell organelle
 It is found in both plant and animal cell
 It is spherical in shape and bounded by double membrane with
many pores
 It also contains the hereditary materials such as Deoxyribonucleic
Acid (DNA) which determines the characteristics of an organism
 DNA directs the synthesis of Ribonucleic acid (RNA) which in turn
directs the synthesis of proteins
 DNA is bound with proteins in the Nucleus to form chromatin,
during cell division the DNA coils more tightly around the proteins
then, condense to form short thickened structures called
chromosomes.
 Nucleus was discovered in 1831-1833 by a botanist Robert Brown

Functions:
 It controls the cell activities
 Nuclear membrane controls movement of materials in and out of nucleus.

12. NUCLEAR MEMBRANE:
 The nuclear membrane is also called the nuclear envelope and encloses the content
of the nucleus of the cell
 It separating the contents of the nucleus from the rest of the cell
 Nuclear pores in the nuclear membrane enable various substances, such as nutrients
and waste products, to pass into and out of the nucleus.

13. ROUGH ENDOPLASMIC RETICULUM (RER):
 RER is a series of interconnecting flattened tubular tunnels that spreads throughout
the cytoplasm.
 Stores and transport proteins both within the cell and from the inside to the outside.

14. SMOOTH ENDOPLASMIC RETICULUM (SER):
 It has same structure with the RER, but just that it lacks ribosomes attached to it and
therefore does not synthesize protein.
It has the following function:
 This is the site of lipid synthesis and secretion within cells, glycogenolysis
(breakdown of glycogen into glucose) and drug detoxification.

LECTURE 7: Cell Growth and Cell Division

Cell Division:
 Process where by a single cell divide into many daughter cells through
a continuous series.
 Cell cycle: Is the entire sequence of events happening from the end of
one nuclear division to the beginning of the next
 Takes place in 16 hours
 Embryonic cells (Cleavage) divide every 20 minutes.
 Occur either through meiosis or mitosis depending on the cell type.

Cell Division:
 The cell cycle involves six stages:
 Interphase: involving four phases, two gap phases (G1 and G2), synthesis phase (S) in
which the genetic material is duplicated and a Mitosis phase (M) in which mitosis
partitions the genetic material and the cell divides after going through prophase,
metaphase, anaphase, telophase and cytokinesis.

Cell Cycle:
 The cell cycle is the complete sequence of events in life of an
individual diploid cell.
 A new cell has four options:
1. It can remain stable, in interphase for many months or years (G0).
Brain cells and other nerve cells rarely divide.
2. It can undergo mitosis within a short period of time. Such as skin cells
and cells of the gut, they have rapid cell cycle.
3. It can undergo meiosis. Specialized germ cells in the ovary and testes
include meiosis in their cell cycle and produce egg cells or sperm.
4. It can choose to die off (Apoptosis or Necrosis).

Types of Cell Cycle:
1.Mitosis cell division
2.Meiosis cell division.

Mitosis:
 Is a form of eukaryotic cell division that is found only in
somatic cells
 It produces two daughter cells with same genetic component as
the parent cell
 Always in diploid form (2n)
 Sole function is to repair and replace damaged cells
 They are also responsible for multiplication of bodily cells that
leads to increase in size.

Mitosis:
 Mitosis cell division involves:
 Interphase: G1, G2, S or G0
 Early Prophase
 Late Prophase
 Metaphase
 Early Anaphase
 Late Anaphase
 Telophase
 Late Telophase and
 Cytokinesis.

Mitosis:

Mitosis: INTERPHASE
 GROWTH 1
 SYNTHETIC
 GROWTH 2
 MITOSIS

MEIOSIS:
 It produces haploid sex cells
 It occurs in testes for male and Ovum for female
 It occurs in gamete cells only
 It is for reproductive cell
 It involves two stages :
Meiosis I
Meiosis II

MEIOSIS I: Stages
 INTERPHASE I (G1, S, G2 and G0)
 EARLY PROPHASE I(Leptotrne and Zygotene)
 LATE PROPHASE I(Pachytene, Diplotene and Diakinesis).
 METAPHAS I
 ANAPHASE I
 TELOPHASE I
 CYTOKINESIS I

INTERPHASE I
GROWTH 1
SYNTHETIC
GROWTH 2
MEIOSIS

PROPHASE I
Prophase I: in Meiosis, prophase is the longest phase. It is divided into:
 Leptotene: Here the centrosome remains un-splitted, the nuclear membrane
remains intact but the chromatin threads attached themselves to the nuclear
membrane and also condensed to form attachments of some dots.
 Zygotene: At this stage, the centrosome still remains same and nuclear
membrane is intact, but the nucleolus disappears. The chromatin threads
separate from nuclear membrane to form a bivalent chromosome. The
homologous chromosomes move close together by synapsis by Synaptonema
complex.
 Pachytene: At this stage, the chromosomes start separating forming tetrads (4).
The chromosomes arms lay close together by chiasmata with an help of a
recombinase enzyme. Exchange of genetic material occur.
 Diplotene: Here, the Synaptonema complex breaks and Terminalization starts.
Terminalization is the process by which two homologous chromosomes zip off
after exchanging genetic materials through chiasmata.
 Diakinesis: Here, the centrosome breaks into two centrioles are moved to
separate poles. Spindle fibers are also formed. This results to chromosomes
having combination of genes from both parents

MEIOSIS II
 INTERPHASE II (G1, S, G2 and G0)
 PROPHASE II
 METAPHAS II
 ANAPHASE II
 TELOPHASE II
 CYTOKINESIS II

INTERPHASE II
 IT IS USUALLYA RESTING STAGE
 GROWTH 1
 SYNTHETIC
 GROWTH 2
 MEIOSIS

THERE IS NO MAGIC
IN BIOLOGY
JUST
READ YOUR BOOK

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