Anatomy of the Cell Flashcards
Name the general components in a cell from most to least
Water protein lipid carbohydrate inorganic
What do all eukaryotic cells contain?
an outer membrane an inner cytosol/cytoplasm a cytoskeleton membrane bound organelles inclusions
What does the
cell membrane do?
Separates inside of cell from outside of cell
Contains integral proteins including receptors, channels, transporters, enzymes and cell attachment proteins.
Can exocytose and endocytose substances across membrane
Why is the cell membrane fluid?
Changes shape easily
Membrane proteins can diffuse laterally (some are anchored)
Why is the cell membrane selectively permeable?
Water, Oxygen and small HYDROPHOBIC molecules can penetrate the membrane
Charged ions cannot penetrate membrane
What does the plasmalemma contain?
integral and peripheral proteins and cholesterol
What is the difference between an organelle and an inclusion?
Organelle - necessary for cell function and survival
Inclusion - dispensable and transient
What do the Mitochondria do?
Produce energy (ATP)
What does the rough endoplasmic reticulum do?
Involved in protein synthesis
What does the smooth endoplasmic reticulum do?
Synthesises and detoxifies cholesterol and lipids
What does the Golgi Apparatus do?
Modifies and packages proteins
Give examples of inclusions
Substances synthesised by cell eg pigments, glycogen stores, lipid droplets,presecretion product
or taken from extracellular envrionment eg endocytotic vesicle
Name the three main classes of filaments
Micro filaments
Intermediate filaments
Microtubules
Describe the Microfilaments
Made of two strands of actin twisted together
7nm diameter
Easy to assemble and disassemble
Describe intermediate filaments
Types divided into classes used to identify origin of tumour in pathology
10 - 15nm
Where are neurofilaments found?
nerve cells
Where are glial fibrillary acidic proteins found?
Glial cells
Where are desmins found?
Muscle cells
Where are cytokeratins found?
epithelial cells
Where are vimentin found?
mesenchymal cells
Where are Filesin found?
lens of eye
Where are lamin found?
Nuclei of all cells
Describe Microtubules
hollow tube made of alternating alpha and beta tubulin
Can assemble and disassemble
Come from centrosome organising centre (CTOC)
What does MAPS stand for?
Microtubule-associated proteins
What do microtubules do?
Transport substances from centre of cell to membrane and back
Important in cilia, flagella, mitotic spindle, and neurons
What are Kinesin and Dynein?
ATPases which associate with organelle/vesicle membranes and transport them along microtubule
Kinesin - to cell periphery
Dynein - to cell centre
What surrounds the nucleus?
Nuclear envelope made of inner and outer membrane
Membranes contain pores to join it up to cytoplasm
What is between the inner and outer layer of nuclear membrane?
Perinuclear cistern which is continuous with the cistern of the endoplasmic reticulum
What is in the outer nuclear membrane?
Ribosomes
is continuous with rough endoplasmic reticulum
Where are mRNA, tRNA, and rRNA transcribed?
mRNA and tRNA in the nucleus
rRNA in the nucleolus
What does the nucleus contain?
Euchromatin - DNA currently undergoing transcription
Heterochromatin - DNA not currently undergoing transcription
Where are ribosomes formed?
In the nucleolus
What is the structure of a ribosome?
Two subunits:
- small unit, binds RNA
- large unit, catalyses formation of peptide bonds
What does reticulum mean?
Net-like structure
What is the endoplasmic reticulum?
Network of interconnecting membrane bound compartments
What does the rough endoplasmic reticulum do?
Containing embedded ribosomes, it is instrumental in the production of proteins which will be placed in the cell membrane/ secreted
What do polysomes produce?
Proteins which will stay in the cytosol
Describe the process of protein synthesis including the RER
Ribosome binds to mRNA
If ER signal peptide sequence present, new peptide will grow into an ER pore
New peptide formed in ER, signal sequence removed
Ribosome detaches and protein moves into SER
What kind of cells contain large quantities of ER?
Cells which are metabolically active
What does smooth endoplasmic reticulum do?
Synthesises lipids
Processes proteins from RER
What is the Golgi apparatus?
Several cisternae bound by membranes which modify and package macromolecules produced in ER
What can the Golgi apparatus do to modify macromolecules?
Add sugars
Cleave proteins
Sort into vesicles
How are macromolecules transported to Golgi apparatus?
In vesicles
describe the structure of a mitochondrion
have an outer and inner membrance
inner membrance is folded, creating cristae which increase the total surface area
contain their own DNA
What does it mean if a cell contains many mitochondria?
Cell is metabolically active
What is an intercellular junction?
List the three types
structures which link the membranes of individual cells together
Occluding junctions
Anchoring junctions
Communicating junctions
What is an Occluding junction?
an area where proteins from both cell membranes interact and hold the cells together
this prevents diffusion between the cells
What other names exist for an occluding junction?
Tight junction or zonula occludens
What is an Anchoring junction?
When Cadherin molecules which span the membrane bind to each other between the two cells
the cadherin is attached to actin in the cytoskeleton via other molecules
What other names exist for anchoring junctions?
Adherent junctions or zonula adherens
What is a desmosome/macula adherens?
Link between the intermediate filaments of the cytoskeleton of two cells
common in epithelial tissue
What is a junctional complex?
Several different junctions found very close together
What is a communicating junction?
A group of pores between two cells which allows some molecules to diffuse through to the other cell
Pores are formed by connexon proteins
Also known as gap junctions
Allows a wave of excitation to spread (cardiac and smooth muscle)
Name the three ways substances can be moved across a cell membrane
Diffusion
By the action of transport proteins
By vesicular transport
What is endocytosis?
When material is brought into a cell by the invagination of the membrane
Receptors can control this process
What is exocytosis?
The opposite of endocytosis
What is phagocytosis?
When a phagocyte takes up material from outside the cell and combines it with lysosomal enzymes to break down the material
What is a;
phagosome?
phagolysosome?
the vesicle containing the material brought in
the phagosome with lysosomal enzymes added
