1-striated muscle cells 2-macrophage engulfing a bacterium 3- plant cell 4- nervoes cell 5- red blood cell 6- stem cell
There are exceptions to these general statements. Red blood cells, for example, do not have a nucleus. Animal cells often have vacuoles but these are small and scattered throughout the cytoplasm.
Very few tissues consist of a single cell type. There are usually nerve fibres and blood vessels supplying the tissue
All cells consist of cytoplasm, nucleus and a cell membrane. The next three slides explain the function of each of these
A cell needs to take up oxygen and food substances to keep it alive. The cell membrane allows these substances to pass into the cytoplasm but keeps unwanted, and possibly harmful, substances out.
Under the ordinary microscope, the cytoplasm appears to be a semi-liquid gel. In some plant cells it can be seen streaming around the cell. Small particles and granules can be observed in the cytoplasm but, under higher magnification, a complex arrangement of microscopic tubules and vacuoles is revealed. These structures enable the chemical reactions, which make the cell alive, to take place in an orderly and controlled manner
The nucleus contains a substance called DNA. This substance controls what kind of a cell is produced, such as a liver cell, muscle cell or blood cell. Chemicals produced by the DNA escape from the nucleus and regulate all the chemical reactions in the cytoplasm. Cells without a nucleus cannot divide.
These cells have been scraped from the inside of the cheek. They are not .stained but viewed by a special type of lighting. The magnification on the print-out is about x 950
The cell membrane is pressed up against the inside of the cell wall by the pressure of the vacuole and is difficult to see.. The cell wall is made of cellulose . It is permeable , that is, it lets water and dissolved substances pass in and out freely. The vacuole contains a solution of chemicals such as salts, sugars and, sometimes, coloured substances (pigments). This solution is called ‘cell sap’. Its outward pressure on the cell wall keeps the cell firm.
These cells are from a moss leaf. The magnification on this page is about x400. Chloroplasts contain a green pigment, chlorophyll , which absorbs sunlight and helps the plant to make its food
Cell and functions unit 1 mine
THE CELL*The Cell Theory.*Types of cells.*Parts of a cell.
All things on earth can be classified into2 groups. Can you group these itemsinto these 2 main groups? LIVING or NON LIVING
All things on earth are either living or non-living. non-livingSo... What makes living things different from Non-living things? Let’s see
There are 7 characteristics:• Movement• Respiration• Sensitivity• Growth• Reproductio n• Excretion• Nutrition
Movement• An action by an organism or part of an organism causing a change of position or place.
Respiration• The chemical reactions that break down nutrient molecules in living cells to release energy (break down + O2) Respiration is NOT *gaseous exchange *BREATHING
Sensitivity• The ability to detect or sense changes in the environment (stimuli) and to make responses (react to them)
Growth• A permanent increase in size and dry mass by an increase in cell number or cell size or both.
Reproduction• The processes that make more of the same kind of organism
Excretion• The removal from organisms of toxic materials, the waste products of metabolism (chemical reactions in cells including respiration) and substances in excess of requirements.
Nutrition• The taking in of nutrients (from environment)which are organic substances and mineral ions, containing raw materials or energy for growth and tissue repair, absorbing and assimilating them.
Quiz Guess which characteristic is beingdemonstrated by the following animations:
CELL THEORY 1. The basic unit of life is the cell. (Hooke)• In 1665, an English scientist named Robert Hooke made an improved microscope and viewed thin slices of cork viewing plant cell walls• Hooke named what he saw "cells" Slide from: http://www.worldofteaching.com
CELL THEORY 2. All living things are made of 1 or more cells.• Matthias Schleiden (botanist studying plants)• Theodore Schwann (zoologist studying animals) stated that all living things were made of cells Slide from: http://www.worldofteaching.com Schwann Schleiden
CELL THEORY3. All cells divide & come from old cells. (Virchow) Virchow
Prokaryotes and Eukaryotes CELLSEukaryotic cell = with nucleusProkaryotic cell = without nucleus BACTERIA Prokaryotic cell Cell membrane Eukaryotic cell Cytoplasm Cell membrane Cytoplasm Organelles Nucleus
Eukaryotic • Contain organelles surrounded by membranes • Most living organisms Plant Animalhttp://library.thinkquest.org/C004535/eukaryotic_cells.html
What are the main parts of a cell? • Cell membrane • Cytoplasm • Nucleus
A section through a liver cell (animal cell):cell membrane nucleuscontrols what contains theenters and DNA and soleaves the cell controls the cell cytoplasm DNA metabolic contains the (chemical) coded reactions instructions to occur here make proteins
Section through a palisade cell of a leaf (plant cell) chloroplastcell membrane Site of photosynthesis large sap vacuole nucleus Storage of nutrients and waste products. cellulose cell wall cytoplasm Provides protections and support for cell
Comparing animal and plant cellsFound in both animal Found only in plant and plant cells cells cell membrane cellulose cell wall nucleus large sap vacuole cytoplasm chloroplast
13 Plant and animal cells• All cells have cytoplasm, a nucleus and a cell membrane.• Plant cells have also a cell wall, a central vacuole and in many cases, chloroplasts.• Animal cells do not have these structures
Red blood cells transport oxygen cell surface membrane cytoplasm contains no nucleus allows more room for haemoglobincytoplasm containshaemoglobinhaemoglobin is aprotein which carries bi-concave disc shapethe oxygen molecules increases surface area over which absorption of oxygen can occur
Muscle cells contract and enable movement of the body muscle Muscle cells have many nuclei cell surface membrane nucleusThe strands of proteinslide over each othermaking the muscle cell(fibre) shorter and causingthe muscle to contract protein strands
Ciliated cells move bacteria and dust away from the lungs cilia Cilia are small extensions of the cell. They beat rhythmically to sweep mucus, which has trapped bacteria and dust, away from the lungs nucleus magnification X3000
Xylem vessels transport water and minerals up the plant xylem vessels are continuous tubes xylem vesselno cytoplasmhollow: allows forcontinuous flow of waterand dissolved mineralions lignin water-proof and strong; helps support the plant cross-section longitudinal section
Root hair cells absorb minerals and water from the soil Cross-section of a root hair cell cell membrane semi-permeable, so will allow water and mineralcytoplasm ions into the cellcontains nochloroplasts as nophotosynthesis isneeded root hair cell increases surface area for absorption of water and mineral ions
A tissue is a group of cell of similarstructure that form a shared function Tissues found in the leaf Animal tissues: muscle tissue upper epidermal tissue palisade mesophyll tissue spongy mesophyll nervous tissue tissue lower epidermal tissueCross-section of a leaf
An organ is a structure made of agroup of tissues working together to perform specific functions heart lungs liver stomach brain kidneys Plant organs include the stem and the leaves
An organ system is a group of organs that coordinate to perform related functionslymphatic digestive reproductive skeletal endocrine system system system system system respiratory excretory muscular nervous circulatory system system system system systemIn plants the shoot is an organ system consisting of leaves and the stem
Levels of organisation cell tissue organ organ organism systemsnerve cell nervous brain nervous Homo sapiens tissue system smallest largest
15 Organs, cells and tissues The stomach is an organ, part of the digestive system The stomach wall contains muscle tissueThe muscle tissue consists ofmuscle cells
4A group of cells from animal tissue cell membranecytoplasm nucleus
7 Cell membraneThe cell membrane encloses thecytoplasm and stops it flowing outIt also controls which substancescan get into and out of the cellIt is only about 0.00001mm thick Double layer cell membraneIf it is damaged, the cell will die
Cell Wall • Most commonly found in plant cells & bacteria • It is made of cellulose. • It supports & protects cellshttp://library.thinkquest.org/12413/structures.html
Cytoplasm• Collective term for cytosol and organelles
5 Cytoplasm The cytoplasm is a living, semi-liquid material cytoplasmAlthough it looks structurelessit contains many structureswhich are not visible at thismagnificationAll the processes which keepthe cell alive, take place in thecytoplasm or nucleus
Cytoskeleton - Composed of microtubules - Supports cell and provides shape - Aids movement of materials in and out of cellshttp://library.thinkquest.org/12413/structures.html
6 Nucleus *The nucleus is a specialised region of cytoplasm which regulates all the chemical changes which take nucleus place in the cytoplasm*It sends chemical signals to thecytoplasm which start or stop thechemical processes going on in it*The nucleus also controls cell division *Separated from cytoplasm by nuclear membrane Contains genetic material - DNA
Nuclear Membrane • Surrounds nucleus • Made of two layers • Openings allow material to enter and leave nucleushttp://library.thinkquest.org/12413/structures.html
Chromosomes • In nucleus • Made of DNA • Contain instructions for traits & characteristicshttp://library.thinkquest.org/12413/structures.html
Endoplasmic Reticulum • Moves materials around in cell • Smooth type: lacks ribosomes • Rough type (pictured): ribosomes embedded in surfacehttp://library.thinkquest.org/12413/structures.html
Ribosomes • Each cell contains thousands • Make proteins • Found on ribosomes & floating throughout the cellhttp://library.thinkquest.org/12413/structures.html
Mitochondria• Produces energy through chemical reactions – breaking down fats & carbohydrates• Controls level of water and other materials in cell• Recycles and decomposes proteins, fats, and carbohydrateshttp://library.thinkquest.org/12413/structures.html
Golgi Bodies • Protein packaging plant • Move materials within the cell • Move materials out of the cellhttp://library.thinkquest.org/12413/structures.html
Lysosome • Digestive plant for proteins, fats, and carbohydrates • Transports undigested material to cell membrane for removal • Cell breaks down if lysosome explodeshttp://library.thinkquest.org/12413/structures.html
Vacuoles• Membrane-bound sacs for storage, digestion, and waste removal• Contains water solution• Help plants maintain shapehttp://library.thinkquest.org/12413/structures.html
Chloroplast• Usually found in plant cells• Contains green chlorophyll• Where photosynthesis takes placehttp://library.thinkquest.org/12413/structures.html
Centrioles• Centrioles are found in animal cells and help to organize the assembly of microtubules during cell division.
17 Question 1Which of these structures controls cell division?• Cytoplasm• Nucleus• Cell membrane• Cell wall
18 Question 2In a plant cell, which of these describes the vacuole?• A semi-liquid living material• A specialized region of cytoplasm• A region containing chloroplasts• A solution of salts and sugars
19 Question 3The cell structure which controls the entry or exit of substances is• the nucleus• The cell wall• The cell membrane• The cytoplasm
20 Question 4 Which one of these statements is correct?•Plant cells do not have cell walls•Plant cells have no vacuoles•Plant cells have nuclei•All plant cells have chloroplasts