cell biology

Question 1

what is the function of the cytoplasm

Answer 1

site of cell reactions

Question 2

what is the function of the cell membrane

Answer 2

controls entry and exit of molecules to cells

Question 3

what is the function of the nucleus

Answer 3

controls cell activities (contains genetic information)

Question 4

what is the function of the ribosomes

Answer 4

site of protein synthesis

Question 5

what is the function of the mitochondria

Answer 5

site of aerobic respiration

Question 6

what is the function of the cell wall

Answer 6

gives the cell support and structure

Question 7

what is the function of the vacuole

Answer 7

contains cell sap

Question 8

what is the function of the chloroplasts

Answer 8

contains chlorophyll. Traps light for photosynthesis

Question 9

what is the function of the plasmid

Answer 9

additional rings of DNA

Question 10

what is the structure of the membrane?

Answer 10

It is made up of proteins and phospholipids. It has a selectively permeable membrane which small molecules like glucose water and oxygen can pass through but larger molecules like starch and fat cannot

Question 11

describe diffusion

Answer 11

diffusion is a form of passive transport. Movement from high concentration to low concentration down a concentration gradient. No energy is required.

Question 12

What is osmosis?

Answer 12

Osmosis is the diffusion of water molecules from a region of high water concentration to a region of lower water concentration through a selectively permeable membrane. Osmosis is a passive process, it does not require energy.

Question 13

what is active transport?

Answer 13

ions/ molecules move from low to high concentration against a concentration gradient. Energy is required, this is an active process.

Question 14

what is a chromosome?

Answer 14

The nucleus of the cell carries genetic information in structures called chromosomes - chromosomes contain DNA

Question 15

what is a gene?

Answer 15

a gene is a section of DNA which codes for making protein to give you a characteristic.

Question 16

describe the structure of DNA

Answer 16

• DNA is a double stranded helix held together by complimentary base pairs
• DNA carries the genetic information for making proteins
• ATGC

Question 17

what are proteins made up of?

Answer 17

proteins are made up of many subunits called amino acids linked together in long chains by peptide bonds

Question 18

how are proteins different from eachother?

Answer 18

each proteins has its own sequence of amino acids. The sequence of amino acids determines the structure and function of the protein.
- the DNA base sequence determines the amino acid sequence in proteins

Question 19

what is messenger RNA?

Answer 19

mRNA is a molecule which carries a complimentary copy of the genetic code from the DNA in the nucleus to a ribosome where the protein is assembled from amino acids

Question 20

what is the cell wall made of?

Answer 20

the cell wall is made of cellulose fibres, it keeps the cell rigid. It resists the uptake of water to maintain the shape and support of the cell. Fungal and bacterial cell walls are not made up of cellulose fibres but do the same job.

Question 21

what are the functions of protein?

Answer 21

antibodies, structural, enzymes, hormones, receptors

Question 22

which molecules are found in the cell membrane and move ions by active transport?

Answer 22

protein molecules

Question 23

why is diffusion important to cells?

Answer 23

diffusion is important to cells and multi cellular animals because cells require glucose and oxygen to diffuse into them so they can release energy during aerobic respiration. During this respiration process cells make the waste product, carbon dioxide which must diffuse out of the cells so they can stay alive.

Question 24

effect of osmosis on plant cells
plasmolysed
stay same
turgid

Answer 24

plasmolysed means when there’s low water the cell shrinks
turgid means when theres too much water the cell swells

Question 25

how is mRNA produced?

Answer 25

- the genetic code is copied to produce a messenger RNA - messenger RNA carries a complementary copy of the genetic code from the DNA out of the nucleus to a ribosome in the cytoplasm - amino acids arrive at the ribosomes and line up according to the sequence of bases on the mRNA - peptide bonds form between the amino acids. This forms a protein molecule.

Question 26

what are enzymes?

Answer 26

enzymes are proteins which are biological catalysts made by all living cells. They speed up chemical reactions and are unchanged in the process

Question 27

what is the purpose of a control experiment?

Answer 27

control experiments are set up to ensure that any change in results are due to the variable that is altered. They have to be identical to the original experiment minus the altered variable.

Question 28

what is a substrate?

Answer 28

A substrate is the molecule on which the enzyme works

Question 29

what happens during an enzyme controlled reaction?

Answer 29

during an enzyme controlled reaction the molecule on which the enzyme works called the substrate joins temporarily onto the active site on the surface of the enzyme. This speeds up the chemical reaction and forms the product(s) an enzyme substrate complex is formed

Question 30

why are enzymes specific?

Answer 30

Enzymes are said to be specific to a particular substrate because the shape of the active site of an enzyme molecule is complementary to it's specific substrate

Question 31

what is a degredation reaction?

Answer 31

a reaction in which large complex molecules are broken down into smaller simpler ones

Question 32

what is a synthesis reaction?

Answer 32

A reaction in which small simple molecules are built up into larger more complex ones

Question 33

PROBLEM SOLVING AND OTHER

Answer 33

- energy pyramids and stuff - cell microscope thing - percentage change - percentage - ratios - look at the diagram of genetic engineering

Question 34

what colour is iodine if starch is present?

Answer 34

blue/ black, if it's not present it's brown

Question 35

when are enzymes most active?

Answer 35

when they are in their optimum conditions.

Question 36

which two factors can affect enzymes and proteins?

Answer 36

pH and temperature

Question 37

what happens to an enzyme when it's not at its optimum pH?

Answer 37

Above and below an enzymes optimum pH the enzyme is denatured, therefore it's activity is reduced

Question 38

what is genetic engineering?

Answer 38

genetic engineering is when genetic information can be transferred from one cell to another

Question 39

what are the steps involved in the genetic engineering process?

Answer 39

1. identify the section of DNA that contains required gene from source chromosome 2. extract required gene 3. extract plasmid from bacterial cell and insert required gene into bacterial plasmid 5. insert plasmid into another host bacterial cell to produce a genetically modified organism 6. genetically modified bacterial cell divides and produces the required product.

Question 40

which steps in the genetic engineering process involve enzymes?

Answer 40

- cutting human DNA to extract the required gene - cutting open the plasmid - sealing the human gene into the bacterial plasmid