Unit 1 - Introduction to Biochemistry.pdf

MAHSA University - Faculty of Engineering
Faculty of Engineering
Unit 1:
Biochemistry of Living Cell
Biochemistry (BEE 4143)

WHAT IS BIOCHEMISTRY?
• Chemistry of life
• A combination of the words biology and chemistry.
• Biology is the study of cells that form the fundamental units of all
living organisms.
• Whereas, chemistry is the science that deals with the composition,
structure, and properties of substances and the transformations that they
undergo.
• Biochemistry seeks to describe the structure, organization, and function
of living matter in molecular terms.

Introduction to Cell
Two basic types of cells
1) Prokaryotes Cells :
Lack of nucleus and membrane
bound organelles

PROKARYOTES
Prokaryotes are single-celled microorganisms
characterized by:
• the lack of a membrane-bound nucleus and
• membrane bound organelles.
There are two domains of prokaryote:
1. Eubacteria / Bacteria
2. Archaebacteria/Archaea

FEATURES OF PROKARYOTIC CELL
• Has five essential structural components:
1.genome (DNA)
2.ribosomes
3.cell membrane
4.cell wall
5.surface layer
• Structurally, a prokaryotic cell has three architectural regions:
1.appendages (flagella and pili)
2.cell envelope (capsule, cell wall , plasma membrane)
3.cytoplasm region (cell genome (DNA) and ribosomes.

Introduction to Cell
Two basic types of cells
2) Eukaryotes Cells :
Have nucleus and membrane
bound organelles

Eukaryotes
• Eukaryotes are animals, plants, fungi, and
protists.
• Human are a eukaryote.
• In addition to having a nucleus, eukaryotic cells
have a number of membrane enclosed
components known as organelles.
• Eukaryotic organisms may be either unicellular or
multicellular. In general, eukaryotic cells contain
much more genetic material than prokaryotic
cells.

EUKARYOTIC CELLS
• Eukaryotic cells are larger than prokaryotes.
• They have a variety of internal membranes and
structures, they are:
1.Organelles
2.cytoskeleton composed of microtubules,
microfilaments and intermediate filaments
• Eukaryotic DNA is composed of several linear
bundles called chromosomes.

Similarities between Eukaryotes and Prokaryotes
• Both have DNA as their genetic material.
1. Both are membrane bound.
2. Both have ribosomes.
3. Both have similar basic metabolism.
4. Both amazingly diverse in forms.

Universal features of living cells
SOµm
1µm
Bacterialcell Animalcell

The Living Cell: Plasma Membrane
A. Surround all cells
- Called Cell Membrane
- Shape and protection
- Boundary
a. Semi-permeable
b. Control movement
of materials in and
out of cells

The Living Cell: Plasma Membrane
B. Membrane Architecture
- Made up of Phospholipid
- Phosphorus Head
• Polar
• Hydrophilic –
attracted to water
- Lipid Tail
• Non-polar
• Hydrophobic – non ‘
attracted to water

Composition of the cell membrane
Phospholipids
Peripheral Proteins
Integral Proteins
Trans – membrane proteins
Cell
Membrane

• Transport across the membranes
• The biological membrane are relatively
impermeable.
• The membrane, therefore forms a barrier for the
free passage of compounds across it.
1. Passive diffusion
2. Facilitated diffusion
3. Active transport

Transport across the cell membrane
• Passive transport does NOT require energy
– Diffusion – small uncharged molecules
– Osmosis - water
– Facilitated diffusion - glucose
• Active transport REQUIRES ENERGY
– Ion pumps
– Endocytosis
– Exocytosis

Active and Passive Transport
Summary

What does the membrane do?
• allows for different conditions between inside
and outside of cell
• subdivides cell into compartments with
different internal conditions
• allows release of substances from cell via
vesicle fusion with outer membrane:

Membrane Permeability
• Biological membranes are physical barriers, but
which allow small uncharged molecules to pass…
• They are described as semi-permeable
Because;
• Lipid soluble molecules and small molecules pass
through
• Big molecules and charged ones do NOT pass
through

Two types of transport
Passive and Active

Passive Transport
• Involves concentration gradients ONLY.
• NO CELL ENERGY is used—this is why it
is called “passive”

Passive Transport
3 types
• Diffusion- simple movement from regions of high
concentration to low concentration.
• Osmosis- specifically the diffusion of water across a
semi-permeable membrane.
• Facilitated diffusion - protein transporters which assist
in diffusion.

Diffusion
Smell Particles & Air
Particles
Solution
Smell Particles diffused
evenly into the Air Particles
Diffusion is the passive movement of particles from a
high concentration of particles to a lower
concentration until they are spread out evenly

Diffusion & Gas Exchange
• Animal cells use oxygen, so oxygen is less concentrated inside the
cell than outside. This causes oxygen to diffuse into the cell
• Carbon dioxide is produced in an animal cell, so it is more
concentrated inside than outside – so it diffuses out of the cell

Facilitated Diffusion
Glucose
Transport protein
Concentration
gradient

Transport Proteins
• Move solutes faster across
membrane
• Highly specific to specific solutes
• Can be inhibited by drugs
• Also involved in ACTIVE
transport

Glucose
Cell membrane
Transport protein
Glucose binds to the
transport protein
The transport protein turns over and releases glucose
onto the inside of the cell, along the concentration gradient
Concentration
gradient

Osmosis
• Osmosis is a special type of diffusion.
• Osmosis is the diffusion of water.
Osmosis is the movement of water
molecules from a high
concentration of water to a low
concentration of water through a
partially-permeable membrane

Osmosis

Class Activity: Correctly Label
Weak Solution
Strong Solution
Solute
Molecule
Water Molecule
Partially Permeable
Membrane
Which way will
the water
flow???

Active Transport
• Cell Energy is used to move substances across the cell
membrane
• The substances are moved against the concentration gradient i.e.
from where there is less to where there is more.

Transport proteins
• Substances are moved molecule by molecule.
• It is similar to facilitated diffusion except that cell
energy (ATP) is used in the process.
ATP = Adenosine Triphosphate

Salt ion
Cell membrane
Transport protein
Ion binds to the
transport protein
The transport protein turns over and releases the ion
onto the inside of the cell, against the concentration gradient
Concentration
gradient
Energy is used

Moving many large molecules at once—
Endocytosis
• Endocytosis
• Transports macromolecules and large particles into the cell.
• Part of the membrane engulfs the particle and folds inward to
“bud off.”
• The cell membrane envelopes the material
• If material is liquid the process is called pinocytosis
• If material is solid the process is called phagocytosis

Pseudopodia extend to engulf food
A food vacuole is formed
Pinocytosis works the same, but with no food, only liquid
How Endocytosis works

Moving many large molecules at
once—Exocytosis
• Material is packaged inside the cell and the
package fuses with the cell membrane while
the material goes out of the cell.

How exocytosis works
Vacuole containing particles
is moved close
to the cell membrane
Fuses with the cell
membrane to expel
the particles
•Animation;
•YouTube - Endocytosis & Exocytosis

Bulk Transport

Passive vs. Active Transport

Transport summary
simple
diffusion
facilitated
diffusion
active
transport
ATP

What distinguishes living organisms?
1. Structurally complicated and highly organized
a. intricate internal structures
b. many kinds of complicated molecules
proteins, DNA, RNA, starches, and lipids etc. (inanimate objects sand clay are mixtures of simple
compounds)
2. Living organisms:
a. extract
b. transform ENERGY
c. store
d. use
47

Biologically important elements
More than 99% of the atoms in animals’ bodies are accounted for
by just four elements—
1. hydrogen (H),
2. oxygen (O),
3. carbon (C)
4. and nitrogen (N).
Hydrogen and oxygen are the constituents of water, which alone
makes up 60–70% of cell mass

All LIVING things are mostly made of 4 types of
molecules called BIOMOLECULES.
BIOMOLECULES are very large
molecules of many ATOMS covalently
bonded together
All BIOMOLECULES contain
CARBON (C)

4 categories of BIOMOLECULES

ENERGY is stored in the COVALENT BONDS
of these large molecules. When we eat, we get
energy to live as chemical reactions within our
bodies break these bonds.
Our bodies can then use the parts of
these large molecules to build new
molecules that build our bodies.

PROTEINS
• Build muscle, bone, structural
support of the cell, etc.
• Function as enzymes to speed
chemical reactions within the body
• Function as pigments and steroid
hormones
Made of many
AMINO ACIDS
bonded together
in a long chain.
C, H, O, N

MONOMER POLYMER CELL STRUCTURE

CARBOHYDRATES
• Store ENERGY
•Provide some structure
Made of many
SUGARS bonded
together in a LONG
CHAIN
Composed of C, H, and O

LIPIDS
• Store ENERGY
• Form cell
membranes
• Act as chemical
messengers (steroid
hormones)
Composed of C, H, and O
A GLYCEROL with 3
FATTY ACID CHAINS
Can be SATURATED or
UNSATURATED depending
on type of BONDS

NUCLEIC ACIDS
• Store genetic information
• Direct the production of PROTEINS
Composed of C, H, N, O, P
Made of many
NUCLEOTIDES
bonded together
in a long chain

Unit 1 - Introduction to Biochemistry.pdf

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