3.4 Eukaryotic cell structure

Question 1

What are the distinguishing features of eukaryotic cells

Answer 1

• Cytoplasm containing membrane bound organelles
• DNA is enclosed in a nucleus

Question 2

Describe the general structure of eukaryotic cells (what organelles do they have) (8)

Answer 2

Cell surface membrane
Mitochondrion
Nucleus
Ribosomes
Rough endoplasmic reticulum
Smooth endoplasmic reticulum
golgi apparatus
Lysosome

Question 3

What are the organelles specific to plant cells (3)

Answer 3

Chloroplasts-in plants and algae
Cell wall-in plants algae and fungi
Cell vacuole- only in plants

Question 4

Describe the structure of the cell surface membrane (3)

Answer 4

• Hydrophilic phosphate heads-points to/ are attracted to water
• Hydrophobic fatty acid tails-point away/repelled from water
• Forms a phospholipid bilayer

Question 5

Describe the function of the cell surface membrane

Answer 5

Selectively permeable-enables control of passage of substances in/out of cell
Receptors on surface which allows cell recognition/signalling

Question 6

Describe the structure of nucleus (5)

Answer 6

• Has a nuclear envelope which is a double membrane
• Nuclear pores
• Nucleoplasm-Granular jelly like material
• Nucleolus-Smaller sphere inside which is the site of rRNA production and makes ribosomes
• Protein/histone bound, linear DNA- Chromatin-condensed

Question 7

Function of Nuclear pores

Answer 7

Allows the passage of large molecules such as mRNA out of the nucleus they are 40-100nm in diameter

Question 8

What is the nuceloplasm

Answer 8

Jelly like material that makes up the bulk of the nucleus

Question 9

Describe the function of the nucleus (4)

Answer 9

Holds/stores the genetic information which codes for polypeptides(proteins)
Site of DNA replication
Site of transcription(part of protein synthesis),producing mRNA
Nucleolus makes ribosomes/rRna

Question 10

Describe the structure of RER and SER

Answer 10

Has lots of ribosomes-RER
Made of a system of membranes called cisternae-SER and RER

Question 11

Describe the function of RER (3)

Answer 11

• Ribosomes are on the surface synthesising proteins
• Proteins processed/folded/transported inside RER
• Proteins packaged into Vesicles for transport e.g. to golgi appartus

Question 12

Describe the function of the SER

Answer 12

• Synthesises and processes lipids e.g. cholesterol and steroid hormones
• Synthesises lipids stores and transports lipids and carbhohydrates

Question 13

Describe the strcuture of a ribosome

Answer 13

• Made of ribosomal RNA
• Protein not a membrane bound organelle

Question 14

describe the function of a ribosome

Answer 14

Site of protein synthesis(translation)

Question 15

What is the difference between 80s and 70s ribosomes

Answer 15

80s-Found in euk is arouond 25nm in diameter
70s-Found in prok smaller than 80s

Question 16

Describe the structure of golgi apparatus and golgi vesicles

Answer 16

Golgi A is flattened membrane sacs
Golgi V are small membrane sacs

Question 17

Describe the fucntion of golgi A (4)

Answer 17

• Modifies proteins e.g. adds carbohydrates to produce glycoproteins
• Modifies lipids e.g. adds carbohydrates to glycolipids
• Packages proteins/lipids into the vesicles
• Produces lysosomes (a type of golgi Vesicle
  transports modifies and stores lipids

Question 18

What is the function of Golgi V

Answer 18

Transports proteins/lipids to desired location e.g. moves to and fuses with cell surface membrane

Question 19

Describe the structure of lysosomes

Answer 19

Has a cell surface membrane and hydrolytci enzymes

Question 20

Describe the function of lysosomes

Answer 20

• To release hydrolytic enzymes(lysozymes)
• To break down/hydrolye pathogens or worn out components

Question 21

Describe the strcucture of mitochondria (3)

Answer 21

• Has a double membrane- controls the entry and exit of matierals
• Cristae-extensions of the inner membrane-provides a large surface area for the attatchment of enzymes
• Matrix contains 70s ribosomes proteins and lipids and DNA

Question 22

Describe the function of mitochondria

Answer 22

Site of areobic respiration
To produce ATP for energy release e.g. for protein synthesis/vesicle movement/active transport

Question 23

Describe the structure of chloroplasts in plants and algae (6)

Answer 23

• Has a double membrane
• Has a stroma which contains
  *thylakoid membrane
• Has 70s ribosomes
• Circular DNA
  -starch granules
  Lamella-thlyakoid linking grana
• Grana-stacks of up to 100 disc like structures called thylakoids- inside the thylakoid is the pigment chlorphyll

grana is also where the first stage of phptosyntehsis takes place

Question 24

Describe the function of chloroplasts in plants and algae

Answer 24

Absorbs light energy for photosynthesis
To produce organic substances e.g. carbohydrates/lipids

Question 25

How are chloroplasts adapted to thier function (3)

Answer 25

* The granal membrane provides a large surface area for the attatchment of chlorophyll * The fluid of the stroma possess all the enzymes needed to make sugars * Chloroplasts contain DNA and 70s ribosomes so they can quickly manufacture the proteins needed for photosynthesis

Question 26

Describe the structure of the cell wall in plants algae and fungi

Answer 26

Composed mainly of cellulose (a polysaccharide in plants/algae Composed of chitin ( a nitrogen-containing polysaccharide in fungi

Question 27

Describe the function of the cell wall in plants algae and fungi

Answer 27

Provides mechanical strength to cell so it prevents cell changing shape or bursting under pressure due to osmosis

Question 28

Describe the structure of the vacuole in plants

Answer 28

Has a tonoplast membrane and contains cell sap | WHen talking about the cell sap talk about the contents in the cell sap

Question 29

What is in cell sap (3)

Answer 29

-sugars, amino acids, waste substances-

Question 30

Describe the function of the vacuole in plants

Answer 30

* Maintains turgor pressure in cell (stopping plant wilting) * contains cell sap which stores sugars, amino acids pigments and any waste chemicals

Question 31

Describe how eukaryotic cells are organised in complex multicellualr organisms

Answer 31

Tissue-Group of specialised cells with a similar structure working together to perform a specific function Organ-aggregations of tissues performing specifc functions Organ system-Group of organs working together to perform specific functions