Cell Structure

Question 1

features of eukaryotic cells

Answer 1

-cytoplasm containing membrane-bound organelle such as chloroplasts and mitochondria so DNA enclosed in a nucleus
-true nucleus
-nuclear envelope surrounding the chromosomes

Question 2

what are most eukaryotic cells part of

Answer 2

complex multicellular organisms containing a range of specialised cells

Question 3

describe the structure of the cell surface membrane

Answer 3

-phospholipid bilayer - molecules embedded within and attached on the outside (proteins, carbohydrates, cholesterol)

Question 4

describe the function of the cell surface membrane

Answer 4

controls the entrance and exit of molecules

Question 5

describe the structure of the nucleus

Answer 5

-nuclear envelope-double membrane
-nuclear pores
-nucleoplasm-granular, jelly like material
-chromosomes-protein bound, linear dna
-nucleolus-smaller sphere in the nucleoplasm which is the site of rRNA production and ribosome synthesis

Question 6

function of the nucleus

Answer 6

-site of DNA replication and transcription (making mRNA)
-contains the genetic code for each cell

Question 7

structure of the mitochondria

Answer 7

-double membrane
-an inner membrane called the cristae
-the fluid centre called the mitochondrial matrix
-contains 70s ribosomes and circular DNA

Question 8

function of the mitochondria

Answer 8

site of aerobic respiration and ATP production

Question 9

structure of the chloroplast

Answer 9

-surrounded by a double membrane
-contains thylakoids (folded membrane embedded with pigment)
-the fluid filled stoma contains enzymes for photosynthesis
-found in plants
-contains 70s ribosomes and circular DNA

Question 10

function of chloroplasts

Answer 10

site of photosynthesis

Question 11

structure of Golgi apparatus and vesicles

Answer 11

-folded membranes making cisternae
-secretory vesicles pinch off from the cisternae

Question 12

function of the Golgi apparatus and vesicles

Answer 12

-add carbohydrates to proteins to form glycoproteins
-produce secretory enzymes
-secrete carbohydrates
-transport, modify and store lipids
-form lysosomes
-molecules are labelled to reach their destination
-finished products are transported to the cell surface in Golgi vesicles where they fuse with the membrane and the contents are released via exocytosis

Question 13

structure of lysosomes

Answer 13

-bags of digestive enzymes-can contain 50 different enzymes

Question 14

function of lysosomes

Answer 14

-hydrolyse pathogens in phagosomes
-completely break down dead cells (autolysis)
-exocytosis- release enzymes outside of the cell to destroy material
-digest worn out organelles for reuse of materials

Question 15

structure of ribosomes

Answer 15

-small granules made up of two sub units of protein and rRNA
-80s-large ribosome found in eukaryotic cells (25nm)
-70s-smaller ribosome found in prokaryotic cells, mitochondria and chloroplasts

Question 16

function of ribosomes

Answer 16

the site of protein synthesis

Question 17

structure of endoplasmic reticulum

Answer 17

-rough and smooth er both have folded membranes called cisternae
-rough er have ribosomes on the cisternae

Question 18

function of rer

Answer 18

protein synthesis on a larger scale

Question 19

function of ser

Answer 19

synthesises and stores lipids and carbohydrates

Question 20

structure of cell wall

Answer 20

-in plants and fungal cells
-plants-made of microfibrils of the cellulose polymer
-fungi-made of chitin, a nitrogen containing polysaccharide

Question 21

function of the cell wall

Answer 21

-provides structural strength to the cell

Question 22

structure of the vacuole

Answer 22

-filled with fluid surrounded by a single membrane called a tonoplast

Question 23

function of the vacuole

Answer 23

-makes cell turgid and therefore provides support
-temporary store of sugars and amino acids
-the pigments are responsible for coloured petals which attract pollinators

Question 24

define specialised cells

Answer 24

a cell whose structure is adapted for its function

Question 25

which are the main 3 adaptations of specialised cells

Answer 25

-large surface area
-high number of mitochondria
-lots of rer and Golgi

Question 26

how does a high surface area affect cells

Answer 26

-maximises the exchange surface
-increased rate of transport
-enables more proteins to be present in the membrane

Question 27

how does a large number of mitochondria affect the cells

Answer 27

-increased rate of respiration
-increase in energy released
-quicker metabolic activities

Question 28

how do lots of rer and Golgi affect cells

Answer 28

-increased protein synthesis
-increased transport of proteins and hormones to where needed
-increased enzyme production
-increased metabolic activity

Question 29

what are the key differences between prokaryotic and eukaryotic cells

Answer 29

-the cells are much smaller
-no membrane bound organelles
-smaller ribosomes (70s)
-no nucleus
-a cell wall made of murein

Question 30

where is dna found in a bacterial cell

Answer 30

-as a single circular molecule in the cytoplasm
-not associated with histone proteins

Question 31

features of prokaryotic cell walls

Answer 31

-do not contain cellulose or chitin which make up cell walls of plants and fungus
-made of a glycoprotein called murein (peptidoglycan)

Question 32

features of some bacteria cells

Answer 32

-plasmids (rings of dna) containing genes linked to survival such as antibiotic resistance
-capsule surrounding cell wall providing protection from other cells and helps bacteria agglutinate
-flagella which are used for locomotion

Question 33

describe viruses

Answer 33

-non living and acellular
-smaller than bacteria
-only contain genetic material, a capsid and attachment proteins