Cell Ultrastructure

Question 1

Structure & function of nucleus

Answer 1

Surrounds chromatin & nucleolus.

Controls activity of cell. Where DNA is stored, replicated and copied into RNA. Nucleus is attached to rough ER so mRNA can easily get to ribosomes.

Question 2

Structure & function of nucleolus

Answer 2

Dense sphere in the center surrounded by nucleus and chromatin.

Where ribosomes are produced. Composed of RNA & proteins.

Question 3

Structure & function of nuclear envelope

Answer 3

Has nuclear pores & forms cisternae to become rough & smooth ER.

A double membrane which compartmentalises nucleus and prevents damage. Protects DNA.

Question 4

Chromatin

Answer 4

Long strands of DNA

Question 5

Structure & function of Rough ER

Answer 5

A system of hollow tubes & membrane bound sacs to form sheets known as cisternae.

Gives a larger surface area for the ribosomes and mRNA to perform protein synthesis.

Question 6

Structure & function of smooth ER

Answer 6

Lacks ribosomes, is a system of interconnected tubes (NOT SHEETS).

Responsible for carbohydrate & lipid synthesis.

Question 7

Structure & function of golgi apparatus

Answer 7

Stacks of flattened membrane bound sacs (cisternae). Vesicles are continuously formed from the ER and break off to form golgi vesicles.

Modifies & processes molecules (new proteins & lipids) and packages them into vesicles.

Question 8

Structure & function of ribosomes

Answer 8

2 subunit organelle. Not membrane bound. Around 22nm in diameter. Found free floating in cytoplasm or on rough ER.

They assemble amino acids in chains using mRNA. Where protein synthesis happens.

Question 9

Structure & function of mitochondria

Answer 9

Surrounded by double membrane. Inner membrane forms windy structure (cristae) to increase surface area. Has mitochondrial DNA to enable them to reproduce create enzymes.

Site of aerobic respiration. Produce ATP.