3.4 Eukaryotic cell structure

Question 1

What does a nucleus contain?

Answer 1

The organism’s hereditary material and controls cell’s activities

About 10-20 μm diameter

Question 2

What parts does the nucleus have? (5 parts)

Answer 2

The nuclear envelope, 
nuclear pores,
nucleoplasm, 
chromosomes (linear DNA, protein bound) 
one or more nucleolus (manufactures rRNA and assembles ribosomes)

Question 3

Functions of the nucleus?

Answer 3

To act as the control centre of the cell through production of mRNA and tRNA and hence protein synthesis

Retain genetic material in the form of DNA and chromosomes

Manufacture ribosomal RNA and ribosomes

Question 4

What shape is a mitochondria?

Answer 4

Rod shaped

1-10 μm in length

Question 5

Structure of mitochondrion?

Answer 5

Double membrane (control entry and exit of material)
Folding of membranes form Cristae

Cristae Extension of the inner membrane, increase surface area for attachment of enzymes and other proteins in respiration

Matrix contains proteins, lipids, ribosomes and DNA

Question 6

Functions of the mitochondria?

Answer 6

Site of aerobic respiration, responsible for producing energy-carrier ATP

Question 7

Give examples of metabolically active cells

Answer 7

Muscle and epithelial cell

Epithelial cells require lots of ATP to absorb substances from the intestine via active transport

Question 8

Give structure of the chloroplast

Answer 8

Chloroplast envelope (double plasma membrane, highly selective)

Grana with (thylakoid stacks) that has photosynthetic pigment (chlorophyll),

Stroma (a fluid filled matrix where sugar synthesis takes place, can also have starch grains

Question 9

What is the function of a chloroplast?

Answer 9

Carry out photosynthesis

Question 10

How are chloroplasts adapted to their functions (harvesting sunlight and carrying out photosynthesis)?

Answer 10

Granal membranes provide large surface area for attachment of chlorophyll and enzymes for 1st PS

Fluid in stroma possess all enzymes needed for 2nd PS

Chloroplasts contain (both DNA and ribosomes) so they can easily manufacture some (proteins) needed for photosynthesis

Question 11

What connects thylakoids?

Answer 11

Lamellae

Question 12

What do chloroplasts produce from CO2 and H20?

Answer 12

Carbohydrates

Question 13

What types of endoplasmic reticulum are there?

Answer 13

Rough ER

Smooth ER

Question 14

How do you differentiate rough ER and smooth ER?

Answer 14

Rough has ribosomes on the outer surface of the membranes;

Smooth does not and look more tubular

Question 15

Function of rough ER?

Answer 15

Provides large surface area for synthesis of proteins and glycoproteins

Provides pathway for the transport of materials, especially proteins (made in ribosome)

Question 16

What is a glycoprotein?

Answer 16

A protein that has a carbohydrate attached to it

Question 17

What is the function of smooth ER?

Answer 17

Synthesise, store and transport lipids

Synthesise, store and transport carbohydrates

Question 18

what kind of cells have a very extensive ER?

Answer 18

Those that manufacture and produce lots of (carbohydrates, proteins and lipids)

Question 19

Where does the ER tend to connect to?

Answer 19

Nuclear membrane

Question 20

Structure of the Golgi apparatus?

3 points

Answer 20

Contains a stack of membranes that make up cistern (flattened sacs)
with rounded hollow vesicles (floating on sides?)

Golgi vesicles regularly pinched off at Golgi cisternae

Vesicles then move to CSM and release insides

Question 21

Functions of the Golgi apparatus?

Answer 21

Add carbohydrates to proteins to form glycoproteins

Produce secretory enzymes (proteins), e.g those form pancreas

Secrete carbohydrates, e.g ones used for making cell walls in plants

Transport, modify and store lipids

Form lysosomes (hydrolytic enzymes)

Question 22

When are lysosomes produced?

Answer 22

When vesicles produced by the Golgi apparatus contains enzymes such as protease and lipase

Question 23

What enzyme do lysosomes contain?

Answer 23

Lysozyme

Question 24

What does lysozyme do?

Answer 24

Hydrolyse the cell walls of certain bacteria

Question 25

What are the functions of a lysosome?

Answer 25

Hydrolyse material ingested by phagocytic cells, e.g WBC and bacteria

Release enzymes to the outside of cells (exocytosis) to destroy material around cells

Digest worn out organelles so useful chemicals can be reused

Completely break down cells after they have dies (autolysis)

Question 26

Where are lysosomes most found?

Answer 26

In secretory cells, such as epithelial cells and phagocytic cells

Question 27

What do ribosomes do?

Answer 27

Synthesise proteins

Question 28

What types of ribosomes are there?

Answer 28

80S (eukaryotic)

70S (prokaryotic)

Question 29

where can ribosomes be found?

Answer 29

Attached onto the rough ER or floating freely in the cytoplasm

Question 30

Why are cell walls so strong?

Answer 30

Have cellulose microfibrils

Question 31

Structure of a cell wall?

Answer 31

Consist of a number of polysaccharides, e.g cellulose

Has a middle lamella to mark boundaries between cells

Question 32

Function of cell wall?

Answer 32

Provide mechanical strength to prevent cell bursting due to osmotic entry of water

Allow water to pass through

Question 33

What do fungi cell walls contain instead of cellulose?

Answer 33

Chitin

Question 34

What are algae cell walls made of?

Answer 34

Cellulose or glycoproteins or both

Question 35

What is the structure of a vacuole?

Answer 35

To contain mineral salts, sugars, amino acids, wastes and sometimes pigements such as anthocyanin

Question 36

What is the function of a vacuole?

Answer 36

Support herbaceous plants

The sugar and amino acids can act as a temporary food store

Pigments can colour petals and attract pollinating insects

Question 37

What is the name of the single membrane around a vacuole?

Answer 37

Tonoplast