Organelles

Question 1

what is a prokaryotic cell?

Answer 1

extremely small ( 0.5 - 5 um)
no membrane bound organelles
no nucleus - free circular DNA
small 70s ribosomes
cell wall made of peptidoglycan
bacteria

Question 2

what is a eukaryotic cell?

Answer 2

larger than prokaryotes (20 - 100um)
has membrane bound organelles (mitochondria)
has a nucleus - linear DNA, has chromosomes
large 80s ribosomes
cell wall made of cellulose in plant cells
call wall made of chitin in fungal cells
animal, plant & fungal cells

Question 3

what are the functions of life?

Answer 3

Movement
Respiration
Sensitivity
Growth
Reproduction
Excretion
Nutrition
(MRS GREN)

Question 4

why are viruses non-cellular?

Answer 4

contain no cytoplasm or organelles
only have RNA or DNA strands

Question 5

what is the interior of the nucleus called and what does it contain?

Answer 5

nucleoplasm
contains chromatin - holds genetic information for making proteins

Question 6

what surrounds the nucleus?

Answer 6

nuclear envelope (double membrane)
with nuclear pores so substances can move in & out

Question 7

what is the dark region of the nucleus?

Answer 7

nucleolus - dark region of chromatin
involved in making ribosomes & RNA

Question 8

what are ribosomes?

Answer 8

found all over the cell but mainly on the rough endoplasmic reticulum (ER)
made of rRNA & have no membrane
made of a large and a small subunit
carry out protein synthesis
70s in prokaryotic cells
80s in eukaryotic cells

Question 9

what is the rough endoplasmic reticulum?

Answer 9

phospholipid bilayer
membrane is continuous with nuclear envelope
cisternae covered with ribosomes responsible for protein synthesis
transports proteins around the cell & to the Golgi body

Question 10

what is the smooth endoplasmic reticulum?

Answer 10

not covered in ribosomes
the site of production & transport of lipids

Question 11

what are vesicles?

Answer 11

secretary vesicles transport glycolipids and glycoproteins to the cell membrane to be secreted by exocytosis

Question 12

what is the golgi body?

Answer 12

receives proteins from ribosomes
proteins and lipids are modified to make glycoproteins and glycolipids
they are package into secretary versicles
produces lysosomes
involved when hormones, proteins, enzymes etc are secreted from a cell

Question 13

what are lysosomes?

Answer 13

contain lytic enzymes which break down bacteria and worn out organelles
used in white blood cells and sperm cells to digest egg material
important for apoptosis (programmed cell death)

Question 14

what is the function of membranes in cells?

Answer 14

surrounds cells and organelles
compartmentalise organelles eg -mitochondria
isolate enzymes & hormones
attachment sites for enzymes & hormones
selective permeability & transport of substances

Question 15

what is the structure of the phospholipid bilayer?

Answer 15

two layers of phospholipids
the outer region (phosphate heads) is hydrophilic
the inner (fatty acid tails) are hydrophobic

Question 16

what are mitochondria?

Answer 16

sites of aerobic respiration
form ATP (energy)
have a double membrane (inner & outer)
have circular DNA and 70s ribosomes
space inside (matrix) where DNA is
can look different shapes if cut at a different angle

Question 17

what is cristae?

Answer 17

folded inner membrane of the mitochondria

Question 18

if circular DNA is maternal which gamete has it come from?

Answer 18

egg cell / ovum

Question 19

what is the cytoskeleton?

Answer 19

network of protein fibres
microfilaments made of actin move against each other allowing cellular movement
microtubules made of tubulin provide strength

Question 20

what is the purpose of the cytoskeleton?

Answer 20

stabilise, supports & strengthens the cell
changes the shape of a cell during exo & endocytosis
holds organelles in place
transport within the cell eg - cytokinesis, movement of RNA & chromosomes
used to move flagella & cilia
make up spindle fibres & centrioles used in cell division

Question 21

how are vesicles and lysosomes transported?

Answer 21

cytoskeleton (microtubules) provide a pathway for vesicles to move on
2 motor types: dynein & kinesin which use ATP
microtubule extends

Question 22

what are centrioles?

Answer 22

small tubes of protein fibres (microtubules)
form the spindle fibres for cell division
spindle fibres move chromosomes during nuclear division
not found in plants

Question 23

what are flagella and cilia?

Answer 23

nine microtubules arranged in a circle with two at the centre
ATP causes movement of the microtubules
need mitochondria & cytoskeleton to function
sperm cells use them

Question 24

what are microvilli?

Answer 24

highly folded plasma membranes of animal cells
increase the surface area for a faster rate of diffusion eg - in the small intestine for absorbing products of digestion

Question 25

why do muscle cells contain large numbers of mitochondria?

Answer 25

mitochondria produce ATP by aerobic respiration muscle cells require lots of ATP for contraction

Question 26

what organises eukaryotic DNA into chromosomes?

Answer 26

histone proteins

Question 27

what are chloroplasts?

Answer 27

double membrane - allows what can enter / exit & takes up water by osmosis contain 70s ribosomes and circular DNA contain grana, thylakoid discs and stroma contain oil droplets for making more phospholipid membranes absorbs light for photosynthesis

Question 28

what are grana?

Answer 28

made of stacks of discs called thylakoids discs have a large surface area for attachment of many chlorophyll molecules linked together by intergranal lamella (membranes) grana = 1 granum = >1

Question 29

what are thylakoid discs?

Answer 29

contain chlorophyll have a large surface area for attachment of many chlorophyll molecules

Question 30

what is the stroma?

Answer 30

inside chloroplasts filled with fluid and starch grains

Question 31

what is the cell wall?

Answer 31

surrounds the cell surface membrane made of cellulose (complex polysaccharide which is freely permeable) provide strength + rigidity as cellulose fibres have high tensile strength to stop the cell from bursting when water enters

Question 32

what is the cell vacuole?

Answer 32

membrane bound organelle found in the cytoplasm contains cell sap (weak solution of sugar, salt & water) surrounded by a membrane (tonoplast) maintains pressure inside the cell & keeps it rigid involved in isolation of unwanted chemicals

Question 33

which organelles are involved in making proteins?

Answer 33

DNA and RNA molecules rough endoplasmic reticulum ribosomes vesicles (transport membrane) golgi body (modification of proteins)

Question 34

how are extracellular proteins produced?

Answer 34

1. transcription 2. translation 3. protein is built in ribosome 4. protein is put into transport vesicles & transported to the golgi body 5. golgi body processes, modifies & packages protein 5. protein packaged into secretary vesicle & moved along microtubule 6. released by exocytosis

Question 35

what are some extra cellular secreted substances?

Answer 35

enzymes (amylase / lipase / protease) protein hormones (insulin) glycoproteins for cell membrane antibodies

Question 36

what is the difference between eukaryotic and prokaryotic DNA?

Answer 36

eukaryotic - linear, has proteins called histones to organise it into chromosomes prokaryotic - circular, no histones so does not form chromosomes

Question 37

what are similarities between prokaryotic and eukaryotic cells?

Answer 37

contains a plasma membrane to control entry and exit of substances in and out of the cell cytoplasm for majority of metabolic reactions ribosomes for protein synthesis DNA that contains coded information for making proteins

Question 38

what is a tissue?

Answer 38

a collection of similar cells that are specialised to work together for a particular function

Question 39

what is an organ?

Answer 39

a collection of different tissues working together for a common function

Question 40

what is an organ system?

Answer 40

a group of organs working together for a particular function