Cell Structure And Functions Flashcards
What is the outermost membrane of a cell?
What is it composed of?
Plasma membrane
Phospholipid bilayer
What is the glycocalyx?
Glycoproteins and glycolipids that project from the plasma membrane
What is a function of the glycocalyx?
Protect the cell from the immune system - shows immunogenicity
What are some functions of the plasma membrane?
- cell recognition and adhesion
- compartmentalisation
- selective permeability
- endocytosis
- exocytosis
What is exocytosis?
Vesicles fusing with the plasma membrane and releasing their contents to the outside
What is endocytosis?
Capturing a substance or particle from outside the cell by engulfing it with the cell membrane, and bringing it into the cell
What does the nucleus contain?
DNA, RNA and nucleoproteins (ribosomes)
What is the dense part of the nucleus?
How would you identify it using a TEM?
Heterochromatin - not active in RNA synthesis
Darker part
What is the less dense part of the nucleus?
Euchromatin - active in RNA synthesis
What happens in the nucleolus?
Site of ribosomal RNA synthesis
What allows the ribosomal subunits to leave the nucleolus?
Nuclear pores
Where are ribosomes assembled?
Rough ER
What is the nuclear envelope a type of?
Specialised ER
Function of RER
Site of ribosomes
Site of protein synthesis
Function of SER (2 specific)
Lipid biosynthesis
Intracellular transport
N-linked glycosylation
Disulphide bond formation
Function of Golgi apparatus
Receives proteins at cis face
Modifies them
Sorts and packages them into vesicles
Proteins leave via trans face
What is the cis face of the Golgi body?
Outer part
Where substances enter from the endoplasmic reticulum for processing
What is the trans face of a Golgi body?
Inner part
Where vesicles detach to assemble into lysosome, secretion or further processing
What do lysosomes contain?
Acid hydrolases
What are lysosomes that have digested their contents by contain indigestible remnants called?
Residual bodies
Where are peroxisomes high in number?
Kidney and liver
They modify toxic molecules before re entering the blood stream
What are peroxisomes that site of?
Oxygen utilisation
Peroxide production
What are the folds of the inner membrane in mitochondria called?
Cristae
Function of mitochondria (2)
Site of of ATP production by oxidative phosphorylation
Act as a Ca2+ store
What is the inner space of mitochondria called?
What does it contain?
Matrix
Enzymes of krebs and fatty acid cycles
What is special about mitochondria?
You inherit all mitochondria from your mother
Three main types of cytoskeleton
Microfilaments
Intermediate filaments
Microtubules
Function of cytoskeleton
- structural support for plasma membrane and organelles
- provides means of movement for organelles
What do Microfilaments bind to to allow contraction?
ATP
Function of intermediate filaments
Tough supporting mesh work in the cytoplasm
They hold the cell together and prevent lysis
Function of microtubules
Originate from centrosome
Attachment proteins can bind to organelles and move them along the microtubules
Why wouldn’t there be a nuclear envelope?
In prophase
It breaks down
To release chromosomes
What is the function of the phospholipid bilayer? (4)
- Allows for selective permeability
- Exocytosis and endocytosis
- Recognition
- Adhesion
What type of molecule is a phospholipid?
What does this mean?
Amphipathic - has a polar head and non-polar tail
What are the two types of secretion from Golgi apparatus?
Constitutive
Signal mediated
What does constitutive secretion mean?
Continuous
What is the cell coat of a lysosome called?
What is it made of?
What is its function?
Glycocalyx
Polysaccharides and oligosaccharides
Stops lysozymes digesting the cell
