cells

Question 1

nucleus

Answer 1

stores dna which determines the development, structure and function of a cell

Question 2

nucleolus

Answer 2

produces ribosomes and rRNA

Question 3

chromatin

Answer 3

DNA wrapped around histones

Question 4

nuclear pores

Answer 4

gaps in the membrane to allow mRNA and ribosomes to pass in and out

Question 5

nuclear envelope

Answer 5

the membrane that surrounds the DNA

Question 6

golgi body/apparatus

Answer 6

sorts, modifies and packages proteins.
e.g adds a sugar unit to a protein to form glycoproteins.

Question 7

ribosomes

Answer 7

site of protein synthesis. which are made of protein and rRNA

Question 8

RER (rough endoplasmic reticulum)

Answer 8

site of protein synthesis, and the transport of proteins(as there are ribosomes attached to the rer)

Question 9

SER (smooth endoplasmic reticulum)

Answer 9

transports and produces lipids, recombines glycerol and fatty acids to form triglycerides)

Question 10

lysosomes

Answer 10

hydrolytic enzymes which breakdown damaged organelles/foreign material
These are kept away from the rest of the cell, or else it would destroy it.
these are formed by the Golgi body

Question 11

mitochondria

Answer 11

site of ATP production by aerobic respiration

Question 12

centrioles

Answer 12

small hollow cylinders and each contain 9 microtubules, which attach onto the chromosomes during mitosis and pull them apart

Question 13

cell membrane

Answer 13

controls what goes in and out of the cell

Question 14

cytoplasm

Answer 14

where all chemical reactions occur

Question 15

chloroplasts

Answer 15

absorbs light energy for photosynthesis

Question 16

cell wall

Answer 16

strengthens the cell and supports it

Question 17

what makes up a prokaryote cell

Answer 17

-cell wall (made up of murein)
-a cell surface membrane
-circular DNA
-ribosomes (smaller than the eukaryote ones)
-cytoplasm

could also have
-capsule surrounding the cell wall
-one or more flagellum
-one or more plasmids

Question 18

what are the differences between prokaryotes and eukaryotes

Answer 18

-E has a nucleus and P doesnt
-E has membrane- bound organelles P doesnt
-E contains mitrochondrandria, RER, SER, golgi body P doesnt
-P has smaller 70s ribosomes and E had 80s ribosomes
-P has circular DNA and E has linear
-P has murein cell wall and E only has a cell wall in plants but does not contain murein

Question 19

features of a mitochondrion

Answer 19

-bounded by two membranes forming an envelope around the inner matrix
-in between the smooth outer membrane and folded inner membrane is the inter-membrane space
-the folds of the inner membrane are called cristae
-matrix contains enzymes for respiration and also DNA and ribosomes
-cells that need large amounts of ATP have many mitochondria

Question 20

name and explain how the structure that is found in epithelial cells and helps the absorbtion of substances in the small intestine

Answer 20

-microvilli
it increases surface area for diffusion

Question 21

whats the difference between TEM microscope and SEM microscope

Answer 21

-TEM gives 2D images whereas SEM gives 3D images
-in TEM the sample must be really thin and stained whereas SEM the sample is coated with a thin film of a heavy metal such as gold
-TEM has a higher resolution than SEM

Question 22

whats the difference between light microscope and electron

Answer 22

-light microscope is cheaper than electron
-electron microscope has a higher resolution and magnification than light microscope
-light microscope has a coloured image whereas electron microscope is black and white
-light microscope uses beam of light to pass through the speciman whereas in electron microscopes they use a beam of electrons focused by electromagnets
-in light microscope speciman can be living but in electron microscope sample has to be dead
-light microscope is very easy to use whereas electron is hard and complex

Question 23

explain why the solution is ice-cold isotonic and buffered in cell centrifugation.

Answer 23

ice cold : to reduce ezyme activity that would break down organelles
isotonic : to prevent osmosis, stops the organelles from shrivelling or bursting
buffered : to maintain the pH and stop enzymes from denaturing

Question 24

whats the order at which the organelles are isolated in cell centrifugation?

Answer 24

• first is nucleus as its the most dense
  -second is mitrochondria/chloroplast as its the next most dense
  -third is ribosomes as its the least dense

Question 25

why is the cell mixture filtered before its spun in cell centrifugation?

Answer 25

to remove cellular debris that may interfere with the results

Question 26

explain why the organelle in sediment C could be seen by a TEM microscope but not a light microscope

Answer 26

because TEM uses a beam of electrons which has shorter wavelenth which gives a higher resolution

Question 27

describe the fluid mosiac structure of the cell surface membrane

Answer 27

-it has a phospholipid bilayer which comstantly moves like fluid -polar phosphate heads facing the outside of the membrane as they are hyrdophilic -fatty acid tails facing the inside on the membrane as theyre hyrdophobic -protein molecules such as channel proteins, carrier proteins and receptor proteins are unevenly distrubuted throughout the membrane forming a mosaic. -very small molecules such as co2 o2 diffuse through the gaps of the phospholipids and water passes through aquaporins(water channel proteins) by osmosis -the phospholipid bilayer allows allows lipid soluble molecules to pass but restricts water soluble and polar molecules -it contains cholestrol to provide support for the membrane and restricts movement of the bilayer

Question 28

diffusion :

Answer 28

the net movement of particles moving from a high concentration to a low concentration

Question 29

whats the equation to work out the rate of diffusion

Answer 29

surface area x concentration difference /diffusion distance

Question 30

facilitated diffusion

Answer 30

allows the transport of poalr molecules(glucose, amino acids) across membranes down a conc gradient using channel/ carrier proteins

Question 31

active transport:

Answer 31

the movement of particles through a partially permeable membrane against the conc grad using energy from atp

Question 32

factors which effect active transport

Answer 32

-lowering temp -lack of oxygen -metabolic/respiratory inhibitors

Question 33

osmosis:

Answer 33

the net movement of water molecules from a high water potential to a low water potential across a partially permeable membrane

Question 34

if a solution has a low solute concentration then it has .. and if it has a high solute concentration it has..

Answer 34

a high water potential a low water potential

Question 35

why do bacteria that cause decay not grow in jam?

Answer 35

Bacteria that cause decay do not grow in jam because the high concentration of sugar creates a hypertonic environment, causing water to be drawn out of the bacterial cells through osmosis, leading to their death.