cell structure and function Flashcards
what is the function of the nucleus of a cell
- control cell activities such as cell growth and the repair of worn-out parts
- contain genetic information in the form of chromosomes to allow for cell division
what is the nuclear membrane
a membrane that separates the contents of the nucleus from the rest of the cytoplasm and has 2 layers of membranes
what is the function of the rough endoplasmic reticulum
it modifies the proteins made by the ribosomes that are attached to its outer surface
how to identify rough endoplasmic reticulum
ribosomes attached to outer surface
outer surface continuous with nuclear envelope
flattened
what is the function of ribosomes
synthesis proteins in the cell (ribosomes attached to the RER make proteins that are transported out the cell, ribosomes lying freely in the cytoplasm make proteins used within the cytoplasm)
function of the smooth endoplasmic reticulum
- synthesise substances such as fats and steroids
- convert harmful substances into harmless ones through the process of detoxification
how to identify smooth endoplasmic reticulum
does not have ribosomes attached to its surface
tubular
function of the mitochondria (singular: mitochondrion)
site of aerobic respiration to produce ATP for cellular activities
how to identify mitochondrion
presence of double membranes (that surround a matrix)
inner membranes fold inwards to form cristae
function of the Golgi body
- chemically modify substances made by the endoplasmic reticulum
- stores and packages substances in vesicles for secretion out the cell or to other organelles in the cell
how to identify Golgi body
comprises cup-shaped series of compartments (cisternae)
function of cytoplasm
jelly-like substance where most cell activities occur
function of cell surface membrane
partially permeable membrane that controls the movement of substances in and out of the cell
function of cellulose cell wall
protects cell from injury and gives the plant cell a fixed shape
function of chloroplast
contain chlorophyll that traps light that is used for photosynthesis to make food for the cell
how to identify chloroplast
presence of double membrane (encloses a fluid filled space called stroma)
function of vacuole
stores substances within the cell
plant cell: large central vacuole that contains sugar, mineral salts and amino acids or serves as disposal of waste materials
animal cell: numerous small vacuoles that exist temporarily and store water and food substances
how are substances made by the endoplasmic reticulum moved out of the cell
- vesicles containing polypeptides made by the rough endoplasmic reticulum pinch off from it
- vesicles fuse with the Golgi body and release the molecules made by the rough endoplasmic reticulum inside. they may be modified by the Golgi body
- secretory vesicles containing such modified molecules pinch off from the Golgi body and move towards the cell surface membrane
- secretory vesicles fuse with the cell surface membrane and their contents exit the cell
types of specialised cells
red blood cell, root hair cell, skeletal muscle cell
definition of differentiation
the process by which a cell becomes specialised for a specific function
structural features of red blood cells
- contain haemoglobin
- have a circular, biconcave shape
- lack a nucleus
- flexible / elastic
why do red blood cells contain haemoglobin
haemoglobin binds to oxygen easily allowing red blood cells to transport of oxygen around the body
why do red blood cells have a biconcave shape
it increases the surface area to volume ratio of the cell so that oxygen can diffuse in and out of the cell at a higher rate
why do red blood cells lack a nucleus
to contain more haemoglobin for the transport of oxygen
why are red blood cells flexible / elastic
allows the cell to change shape easily and squeeze through narrow blood capillaries easily
structural features of root hair cell
- has a long and narrow extension
- low water potential in cell (not really structural feature but)
why do root hair cells have long and narrow extensions
increases the surface area-to-volume ratio for the cell to absorb water and mineral salts at a higher rate
why do root hair cells have a low water potential
increase the rate of osmosis of water into the root hair cell
structural features of skeletal muscle cells
- elongated and cylindrical in shape
- contain many mitochondria
- contain many nuclei
why are skeletal muscle cells elongated and cylindrical in shape
to contain contractile protein fibres
why do skeletal muscle cells contain many mitochondria
to provided more energy for the contraction of the muscle cell
why do skeletal muscle cells contain many nuclei
allows the cells to acquire more oxygen and nutrients to produce more energy
