Cells Flashcards
What is the lipid bilayer?
Two tail to tail later of lipid molecules that form the plasma membrane
What three types of lipids are present in the lipid bilayer and at what distribution?
Phospholipids, contain phosphorus (≈75%)
Cholesterol, a steroid with an attached hydroxl (≈20%)
Glycolipids, lipids attached to carbohydrate groups (≈5%)
What are amphipathic molecules?
Molecules with polar and non polar parts
What parts of phospholipids are polar and non-polar?
Polar phosphate containing heads
Non-polar fatty acid tails
What are integral membrane proteins?
Proteins that extend through the lipid bilayer and are strongly embedded in them
Are integral membrane proteins amphipathic and non-amphipathic?
Amphipathic
What are peripheral proteins?
Proteins not firmly embedded in the membrane. They associate loosely with the integral membrane proteins and lipids
What are the main functions of membrane proteins?
Immunological roles
Acting as receptors for hormones and other chemical messengers
Acting as enzymes
Substance transport across the membrane
What are the types of passive transport across the cell membrane?
Simple diffusion (lipid soluble materials)
Channel mediated-facilitated diffusion (water soluble materials)
Carrier mediated-facilitated diffusion (materials unable to diffuse unaided)
What are the two forms of active transport?
Pumps (sodium ions, potassium ions, calcium ions etc.)
Transport in vesicles (proteins, enzymes, hormones, neurotransmitters etc.)
What are the two forms of vesicular transport?
Endocytosis - in
Exocytosis - out
What proportion of the cell volume is formed by the cytosol?
55%
What is the make up of cytosol?
Water (75-90%)
Disolved and suspended components such as:
Ions
Glucose
Amino acids
Proteins
Lipids
ATP
Waste products
What 3 protein filaments make up the cytoskeleton?
Microfilaments
Intermediate filaments
Microtubules
What is the function of the cytoskeleton?
Maintains cell shape and general organisation
Cell movement
What is this organelle and its function?
Centrosome (A pair of centrioles and surrounding pericentriolar material)
Contains tubulins which are used to form mitotic spindles which move chromosomes during cell division
What is this organelle and its function?
Cilia, moves extracellular fluids
What is this organelle and its function?
Flagella, moves the cell itself
What is this organelle and its function?
Ribosome, synthesises proteins from amino acids using mRNA. Can be either free or attached to endoplasmic reticulum
What is this organelle and its function?
Endoplasmic reticulum, rough (attached to ribosomes and nuclear envelope) and smooth (branches off from rough).
Rough ER: synthesises glycoproteins and phospholipids
Smooth ER: synthesises fatty acids and steroids, inactivates drugs and releases Ca++ in muscle cells
What is this organelle and its function?
Golgi apparatus (Entry face, medial cisternae and exit face). Transports modifies and packages lipids and proteins from the ER into vesicles for delivery to targeted destinations
What is a lysosome?
A vesicle that contains digestive enzymes
What is a peroxisome?
A vesicle that contains oxidases and catalase
What is the purpose of peroxisomes?
Oxidises amino acids and fatty acids
Deactivates toxic material (e.g. alcohol or hydrogen peroxide)
What is this organelle and its function?
Mitochondrion containing a large folded membrane full with enzymes. It synthesises ATP - site for aerobic respiration
What’s the structure of the nuclear envelope?
Double membrane, both lipid bilayers.
Which layer of the nuclear envelope is continuous with the rough ER?
The outer later
What is the purpose of nuclear pores?
Controlling substance movement between the nucleus and cytoplasm
What molecules can pass through nuclear pores passively?
Small molecules and ions
What molecules must pass through nuclear pores by active process?
Large molecules such as RNA and proteins
Where are ribosomes produced?
The nucleoli
What are the components of the nucleolus?
A cluster protein, DNA and RNA
Is the nucleolus enclosed or un-enclosed?
Un-enclosed
