Cells

Question 1

Nucleus?

Answer 1

Genetic material (development structure and function)
Bound by double membrane= nuclear envelope
Nuclear pores allows communication with cytoplasm

Question 2

Function of nucleus?

Answer 2

Nucleus linear DNA associated with histones and one or more nucleoli(RNA)
Controls protein synthesis
DNA and proteins in form of chromosomes

Question 3

Ribosomes?

Answer 3

-very small organelles
-made up of protein and ribosomal RNA
-can be in the cytoplasm singly or attached to RER
-used in protein synthesis joining amino acids together

Question 4

Endoplasmic reticulum?

Answer 4

Consist of flattened sacs which form an internal transport system in the cell

Question 5

Function of endoplasmic reticulum?

Answer 5

RER has ribosomes that produce secretory proteins
Secretory proteins sent to Golgi A for modification and/or packaging
SER lacks ribosomes so produces and transfers lipids

Question 6

Endoplasmic reticulum?

Answer 6

Consist of flattened sacs which form an internal transport system in the cell

Question 7

Golgi apparatus
Golgi vesicles?

Answer 7

Golgi A consists of flattened, membrane sacs

Question 8

Function of Golgi apparatus
Golgi vesicles?

Answer 8

• adds carbohydrates to proteins received from RER-> glycoprotein formed
  -packages glyco/proteins into Golgi V for secretion
  -produce lysosomes (type of GV releases lysozyme (hydrolytic enzyme)

Question 9

Lysosomes?

Answer 9

Simple sacs containing hydrolytic enzymes surrounded by a single membrane
Have to be kept apart from the rest of cell or they’ll be destroyed
Formed by Golgi A

Question 10

Function of lysosomes pt1

Answer 10

Digestion of material taken by phagocytosis- lys fuse with vesicles formed during phagocytosis , releasing hydrolytic enzymes which digest material inside

Question 11

Function of lysosomes pt2

Answer 11

Non-functioning organelles within the cell may be engulfed and digested within lysosomes

Question 12

Function of lysosomes pt3

Answer 12

Release of enzymes outside the cell- sometimes the enzymes of lysosomes are released from the cell

Question 13

Mitochondria?

Answer 13

Involved in aerobic respiration which produces ATP
Often in rod shaped

Question 14

Function of mitochondria pt1

Answer 14

Bounded by two membranes forming an envelope around an inner matrix
Outer smooth membrane and inner folded membrane is the inter membrane space
Folds of inner membrane= cristae

Question 15

Function of mitochondria pt2

Answer 15

Matrix contains enzymes for respiration and also contains DNA and ribosomes
Cells requiring large amounts of ATP have numerous mitochondria

Question 16

Chloroplast

Answer 16

Only found in photosynthetic plants cells and algae
Flattened biconvex discs surrounded by envelope consisting of two membranes

Question 17

Isotonic solution (homogenisation condition)

Answer 17

Prevents the osmotic movement of water in or out of organelles which might cause them to burst or shrivel

Question 18

Low temperature (homogenisation condition)

Answer 18

Prevents the action of hydrolytic enzymes within the cells that might cause self-digestion of the organelles
Low kinetic energy minimises enzyme reaction

Question 19

Buffer solution (homogenisation condition)

Answer 19

Maintains the pH so that proteins, particularly enzymes are not denatured

Question 20

Mitosis

Answer 20

Type of nuclear division Increases cell number for growth and repair of tissues

Question 21

Interphase

Answer 21

Longest time period of the cell cycle
Rapidly dividing cells interphase is short enabling rapid multiplication and replacement of cells

Question 22

Interphase process

Answer 22

DNA content is doubled via DNA replication
Increase in protein synthesis
Cell organelles are replicated
Chromosomes arent visible under optical microscope
Nuclear membrane and nucleolus still present

Question 23

Prophase

Answer 23

Due to DNA replication during interphase each chromosome consist of two identical sister chromatids joined together by a centromere
Chromosome then shortens and thickens
Centrioles move to opposite poles
Nuclear membrane breaks down

Question 24

Metaphase

Answer 24

Centrioles in animal cells form spindle (contain protein microtubules) across the cell
Each chromosome moves to the equator- spindle and attaches to it via its centromere

Question 25

Anaphase

Answer 25

Centromere spilts and sister chromatids separate Chromatids are pulled to opposite poles of the cell by spindle microtubules

Question 26

Telophase

Answer 26

Chromatids are at opposite poles of the cell and begin to uncoil Nuclear membrane reforms Two cells are genetically identical Two nuclei visible under an optical microscope

Question 27

Carrier proteins

Answer 27

Possess a specific tertiary structure complementary to polar molecules (glucose, amino acids) aiding their transport by facilitated diffusion and active transport

Question 28

Channel proteins

Answer 28

Have a specific tertiary structure, which together with its charge and size determines which molecules can be transported across the membrane by facilitated diffusion

Question 29

Protein molecules

Answer 29

Spanning the membrane act as carriers or channels which aid the passage of water soluble ions and polar molecules across the membrane

Question 30

Branched carbohydrates

Answer 30

Chains stick out from the outer surface of some membranes Attached to lipids forming glycolipids or to proteins forming glycoproteins Act as receptors- glycoproteins involved in cell-cell recognition and act as antigens

Question 31

Cholesterol

Answer 31

Provides strength to membrane and restricts the movement of phospholipids so that membrane is less fluid and less ions are loss from the cell

Question 32

Centrifugation

Answer 32

Separates structure of different density Separate and isolate the different organelles in a cell Cells first broken open by grinding a tissue using a blender

Question 33

Centrifugation pt1

Answer 33

Homogenate is filtered to remove intact cells and cell debris that would contaminate the organelles

Question 34

Centrifugation pt2

Answer 34

Homogenate spun in centrifuge most dense organelles form a pellet (sediment) less dense remain in the supernatant