1.1.1 A large organelle surrounded by a nuclear
envolope which contains many pores. The nucleus
contains chromatin and often a nucleolus.
22.214.171.124 Nuclear envolope: Double membrane surrounding nucleus,
continuous with the ER. Controls entry and exit of materials in and out
of the nucleus and contains the reactions taking place within it
126.96.36.199 Nuclear pores: Allow the passage of large molecules, such as RNA, out of the nucleus.
188.8.131.52 Nucleoplasm: Granular and jelly like, makes up the bulk of the nucleus
184.108.40.206 Chromatin: DNA found in the nucleoplasm. This
is the diffuse form that chromosomes take when the
cell isnt dividing. This controls the cells activities.
1.2.1 Act as the control centre of the cell through the
production of mRNA and hence protein synthesis
1.2.2 Retain genetic information
1.2.3 Manufacture ribosomal RNA and ribosomes
2.1.1 Usually oval shaped. They have a double
membrane - the inner one is folded to form
structures called cristae. Inside is the matrix, which
contains enzymes involved in respiration.
220.127.116.11 Double membrane: Outer one controls entry and exit of material. Inner membrane forms cristae.
18.104.22.168 Cristae: Shelf like extensions of the inner membrane. Some extend across the whole width of the
mitochondrion. Provide large surface area for the attachment of enzymes involved in respiration.
22.214.171.124 Matrix: Makes up the remainder of the mitochondrion. Semi rigid, and contains protein, lipids and traces of DNA that
allow the mitochondria to control the production of their own proteins. Enzymes involved in respiration are found here.
2.2.1 Sites of certain stages of respiration
126.96.36.199 Krebs cycle
188.8.131.52.1 A series of chemical reactions used by all aerobic organisms to generate energy through the oxidation of acetate derived
from carbohydrates, fats and proteins into carbon dioxide and chemical energy in the form of adenosine triphosphate (ATP).
184.108.40.206 Oxidative phosphorylation pathway
220.127.116.11.1 Oxidative phosphorylation (or OXPHOS in short) is the metabolic pathway in which the mitochondria in cells
use their structure, enzymes, and energy released by the oxidation of nutrients to reform ATP.
2.2.2 Responsible for the
production of ATP
18.104.22.168 More mitochondria in cells which
have a high level of metabolic
3 Endoplasmic Reticulum
3.1 2 Types of ER: Smooth and rough
22.214.171.124.1 System of membranes enclosing fluid filled space.
126.96.36.199.1 Synthesise, store and transport lipids
188.8.131.52.2 Synthesise, store and transport carbohydrates
184.108.40.206.1 Similar to smooth, but covered in ribosomes
220.127.116.11.1 Provide a larger surface area for the synthesis of proteins and glycoproteins
18.104.22.168.2 Provide a pathway for transport of materials
3.2.1 An elaborate, 3D system of sheet-like
membranes, spreading through the
cytoplasm of the cells. It is continuous
with the nuclear membrane. The
membranes enclose flattened sacs called
cisternae. There are two types of ER.
4 Golgi Apperatus
4.1.1 A group of fluid filled flattened sacs. The
golgi apperatus occurs in almost all
eukaryotic cells and has a similar structure
to the SER except it is more compact.
22.214.171.124 Cisternae: A stack of membranes make up flattened sacs called
cisternae, with small rounded hollow structures called vesicles.
4.2.1 Proteins and lipids produced in the ER are passed through the
Golgi apperatus in a strict sequence. The Golgi modifies proteins
often adding non-protein components. It also 'labels' them, allowing
them to be accurately sorted and sent to their correct destinations.
Once sorted, the modified proteins and lipids are transported in
vesicles which are regularly pinched off from the ends of the Golgi
cisternae. The vesicles move to the cell surface where they fuse
with the membrane and release their contents to the outside.
126.96.36.199 Add carbohydrate to proteins to form glycoproteins
188.8.131.52 Produce secretory enzymes, such as those secreted by the pancreas
184.108.40.206 Transport, modify and store lipids
220.127.116.11 Form lysosomes
5.1.1 A round organelle surrounded by a membrane, with no clear internal structure
5.2.1 Lysosomes are formed when the vesicles produced by the Golgi apperatus contain enzymes
such as proteases and lipases. Lysosomes isolate potentially harmful enzymes from the rest of
the cell before releasing them, either to the outside or into a phagocytic vesicle within the cell.
18.104.22.168 Phagocytic vesicle: Cells that protect the body
by ingesting harmful foreign particles, bacteria,
and dead or dying cells.
22.214.171.124 Break down material ingested by phagocytic cells
126.96.36.199 Release enzymes to the outside of the cell (exocytosis) in order to destroy material around the cell
188.8.131.52.1 Exocytosis: The durable, energy-consuming process by
which a cell directs the contents of secretory vesicles out
of the cell membrane and into the extracellular space.
184.108.40.206 Digest worn out organelles so to reuse useful chemicals
220.127.116.11 Completely break down cells after they have died (autolysis).
18.104.22.168.1 Autolysis: The destruction of a cell through
the action of its own enzymes. It may also
refer to the digestion of an enzyme by
another molecule of the same enzyme.
6.1.1 A very small organelle that floats free in the
cytoplasm of a cell or is attached to the rough ER.
Small cytoplasmic granules.
22.214.171.124 2 subunits: One large and one small.
126.96.36.199.1 Each contains ribosomal RNA and protein. They
can occur in such vast numbers that they can
account for up to 25% of the dry mass of a cell.
188.8.131.52 2 types depending on where they are found
184.108.40.206.1 80S Type: Found in eukaryotic cells, around 25nm in diameter
220.127.116.11.2 70S Type: Found in prokaryotic cells, slightly smaller
6.2.1 The site where proteins are made
7.1.1 Small finger-like projections of the epithelial cell,
folds in the plasma membreane that increase the
surface area to allow more efficient absorption.
7.2.1 Found on cells incolced in absorption, such
as epithelial cells in the small intestine.
18.104.22.168 Increase surface area for diffusion
22.214.171.124 Thin walled, decreasing diffusion pathway
126.96.36.199 Move to help maintain a concentration gradient
188.8.131.52 Well supplied with blood vessels so that blood can carry away absorbed molecules and hence maintain concentration gradient
8 Plasma Membrane
8.1.1 The membrane is found on
the surface of animal cells and
just inside the cell wall of plant
cells and prokaryotic cells. It's
made mainly of lipids and
184.108.40.206 Phospholipid bilayer
220.127.116.11.1 Hydrophilic head
18.104.22.168.1.1 Interacts with water, not with fat
22.214.171.124.2 Hydrophobic tail
126.96.36.199.2.1 Interacts with fat, not with water
188.8.131.52.3 One layer of phospholipids has heads pointing inwards (interacting with water in the cytoplasm)
184.108.40.206.4 The other layer has its hydrophilic heads pointing outwards (interacting with water surrounding the cells)
220.127.116.11.5 Hydrophobic tails of both layers point into the centre of the membrane
18.104.22.168.1 Extriinsic proteins
22.214.171.124.1.1 Occur either on the surface of the biilayer or partially
embedded in it, but never extend completely across it.
Give mechanical support and act as cell receptors for
molecules such as hormones
126.96.36.199.2 Intrinsic proteins
188.8.131.52.2.1 Completely span the phospholipid bilayer. Some act
as carriers to transport water-soluable material
across the membrane whilst others are enzymes
184.108.40.206 Allow lipid-soluable
substances to enter
and leave the cell
220.127.116.11 Prevent water soluable substances
entering and leaving the cell
18.104.22.168 Make the membrane flexible
22.214.171.124 Provide structural support
126.96.36.199 Act as carriers
188.8.131.52 Allow active transport
184.108.40.206 Form recognition sites by identifying cells
220.127.116.11 Help cells adhere together
18.104.22.168 Act as receptors (eg. for hormones)
22.214.171.124.1 Hormone receptors: A molecule that can bind to a specific hormone. Receptors for peptide hormones tend to be found on the
plasma membrane of cells, whereas receptors for lipid-soluble hormones are usually found within the cytoplasm. Upon hormone
binding, the receptor can initiate multiple signaling pathways which ultimately lead to changes in the behaviour of the target cells.
9.1.1 For storage
9.1.2 Gives shape
9.2.1 Contains gelly like mix of chemicals
9.2.3 Contains all organelles
10.1.1 For movement in prokaryotes
11.1.1 Used during cell division
126.96.36.199 Migrate to opposite poles, produce microtubules
of the spinders that pull chromosomes apart