Cell Structure And Function

Question 1

Structure and function of
Nucleus

Answer 1

Structure , 5 micrometer in diameter
Function , stores DNA and synthesizes mrna from dna transcription

Question 2

Structure and function of
Nuclear envelope

Answer 2

Structure: lipid bilayer, contains pores, lined by nuclear lamina

Function: contains pore complexes which control transport across the envelope

Question 3

Structure and function of
Nucleolus

Answer 3

Structure: densely stained granules associated with chromatin

Function: the site of ribosomal RNA , synthesis and assembly

Question 4

Structure and function of
Chromatin

Answer 4

Structure: DNA and associated proteins
Function: coils and condenses into chromosomes for cell division

Question 5

Structure and function of
Ribosomes

Answer 5

Structure: large and small sub units , made from rrna and contains trna, mrna used as template in between subunits
Function: carry out protein synthesis using mrna (translation)

Question 6

Structure and function of
ER

Answer 6

Structure: Extensive network of tubules and sacs (cisternae) high surface area to volume ratio

Function: production,processing and transport in proteins and lipids

Question 7

Structure and function of
RER

Answer 7

Structure: contains ribosomes on outer surface
Function: secreting cells have more rer, polypeptides from bound ribosomes and threaded into er lumin , protein synthesis

Question 8

Structure and function of
Golgi

Answer 8

Structure: membranous cisternae in sacks that aren’t physically connected

Function: receives transport vesicles and stores and further modifies them using enzymes, functional polarity , receives cis and dispatches trans , called maturation process

Question 9

Structure and function of
Lysosomes

Answer 9

Structure: membrane bound vesicles produced by Golgi
Functions: contains hydrolytic enzymes( catalyse hydrolysis), release nutrients from food and break down unwanted molecules, for phagocytosis and for programmed cell death

Question 10

Structure and function of
Peroxisome

Answer 10

Structure: small membrane enclosed organelle containing enzymes for metabolic reactions

Function: do not bud from endo membrane system, contain oxidative enzymes

Question 11

Structure and function of
Mitochondria

Answer 11

Structure: outer membrane , inner membrane, inter membrane space, cristae, mitochondrial matrix

Function: sites of cellular respiration, have their own ribosomes and dna , can synthesise their own proteins, generate atp, and some metabolic steps occur in them

Question 12

What are the 3 components of the cytoskeleton

Answer 12

Actin filaments , intermediate filaments, microtubules

Question 13

Describe the structure and function of an Actin filament

Answer 13

Contains two chains of globular actin monomers twisted together in a helical manner

They interact with motor molecules, which are proteins that attach and detach to them to help them move. The lamellipodium extends when short actin filaments turn into long actin filaments, this causes the rearrangement of actin cytoskeleton to the leading edge which then helps the cell move.

Question 14

Describe the structure and function of intermediate filaments

Answer 14

Ropelike assembly of fibrous poly peptides , a sheet of tetramers

Role in maintaining structural integrity of cell and resisting mechanical stress , can help cells stick together.

Question 15

Microtubules structure and function

Answer 15

Small hollow cylinders , made of globular protein tubulin of alpha and beta types , they have 13 rows of them dimers, they can grow by adding tubulin dimers to their ends.

Support the cell , alter cell shape , serve as tracks for intercellular transport , assist in cell division , cellular locomotion

Question 16

Q1
Using three organelles of animal cells
Explain how their structure relates to their function

Answer 16

3 marks for each organelle 1 for fully linking structures and functions, 1+ for a correct function 1+ for correct structure only 3 marks for both land linked

Best organelles to do
Mitochondria
Rough ER
Nuclear envelope
Cell membrane