2.4 Eukaryotic cell structure

Question 1

what are prokaryotic cells

Answer 1

cells with no membrane-bound nucleus or organelles

Question 2

what are eukaryotic cells

Answer 2

cells with a nucleus and other membrane-bound organelles

Question 3

nucleus (function)

Answer 3

• contains DNA

- controls metabolic activities

Question 4

nucleus (structure)

Answer 4

• DNA in double membrane (nuclear envelope) for protection

- nuclear pores to allow molecules in and out

Question 5

what does DNA do in the nucleus

Answer 5

• associate with proteins called histones to form chromatin

- chromatin coil/ condenses to form chromosomes

Question 6

describe the nucleolus

Answer 6

• in nucleus
• produces ribosomes
• composed of proteins and RNA

RNA —> rRNA+proteins —> ribosomes

Question 7

mitochondria (structure)

Answer 7

• double membrane (inner = folded to form cristae and fluid interior = matrix)
• membrane forming cristae = enzymes for aerobic respiration
• contain mitochondrial (mt)DNA

Question 8

mitochondria (function)

Answer 8

• site of cellular respiration
• energy made available to cell by ATP production
• active cells = more mitochondria
• can produce enzymes and reproduce themselves

Question 9

describe vesicles

Answer 9

• membranous sacs used for storage/transport

- single membrane with fluid inside

Question 10

describe lysosomes

Answer 10

• specialised vesicles with hydrolytic enzymes

- break down waste materials

Question 11

cytoskeleton (structure)

Answer 11

• microfilaments
• microtubules
• intermediate fibres

Question 12

what are microfilaments

Answer 12

• contractile fibres formed from actin

- responsible for cell movement and cell contraction in cytokinesis

Question 13

what are microtubules

Answer 13

determine shape of cell and act as tracks for organelle movement
make up spindle fibres

Question 14

what are intermediate fibres

Answer 14

give mechanical strength to cells and maintain integrity

Question 15

function of cytoskeleton (4)

Answer 15

• provides mechanical strength, support and structure for the cell
• maintains cell shape
• enables movement of organelles inside the cell
• enables movement of the whole cell

Question 16

describe the centrioles

Answer 16

• involved in organisation of the microtubules that make up cytoskeleton
• form spindle fibres
• role in positioning of flagella and cilia

Question 17

describe cilia

Answer 17

• small hair-like extension on cell-surface membranes
• contain microtubules
• work in synchronised fashion
• move organism or fluid across a surface

Question 18

describe flagella

Answer 18

• large extension of cell-surface membrane containing microtubules(eukaryotes)
• beat to enable locomotion or move fluids

Question 19

smooth endoplasmic reticulum

Answer 19

lipid + carbohydrate synthesis and storage

Question 20

rough endoplasmic reticulum

Answer 20

• ribosomes bound to the surface
• synthesises+transports proteins

secretory cells = more RER

Question 21

describe ribosomes

Answer 21

• not surrounded by membrane
• made from RNA in nucleolus
• site of protein synthesis

Question 22

describe the Golgi apparatus

Answer 22

• compact structure made of cisternae

- modifies and packages proteins into vesicles

Question 23

steps of protein production

Answer 23

1. proteins made at ribosomes
2. new proteins folded and processed in RER
3. transported in vesicles from RER to Golgi apparatus
4. proteins are further processed
5. proteins enter more vesicles and are transported around the cell (glycoproteins =secreted from cell surface)

Question 24

ribosomes in the RER and cytoplasm

Answer 24

RER= proteins excreted or attached to cell membrane

cytoplasm = proteins that stay in the cell