Topic 1 - Genes and enzymes

Question 1

What 4 things does an animal cell have ?

Answer 1

1. Nucleus - contains the DNA
2. Cytoplasm - Chemical reactions happen here
3. Cell membrane - holds the cell together
4. Mitochondria - where most of the reactions take place for respiration

Question 2

What 7 things does a Plant cell have ?

Answer 2

1. Nucleus - contains the DNA
2. Cytoplasm - Chemical reactions happen here
3. Cell membrane - holds the cell together
4. Mitochondria - where most of the reactions take place for respiration
5. Rigid cell wall - gives support
6. Large vacuole - contains cell sap
7. Chloroplasts - photosynthesis hapeens here and contains green subtance (chlororphyll)

Question 3

What 4 things does a bacteria cell have ?

Answer 3

1. Chromosonal DNA - controls cells activitys and replication in the cytoplasm
2. Plasmids - extra DNA
3. Flagellum - allows the bactrium to move
4. Cell wall - support

Question 4

What is the calculation to work out magnification ?

Answer 4

Length of image / length of specimen

Question 5

What is DNA ?

Answer 5

• a Double helix of paired bases
• Held together by four different bases that are paired together in always the same way A&T C&G - base pairing
• Bases are joined by weak hydrogen bonds

Question 6

What are the four bases that hold the DNA molecule together ?

Answer 6

(A) Adenine & (T) Thymine

(C) Cytosine & (G) Guanine

Question 7

What is a gene ?

Answer 7

• A section of DNA

Question 8

Who discovered the structure of DNA and how did they do it ?

Answer 8

• Watson, Crick, Franklin, Wilkins
• Franklin & Wilkins - Beams of x-ray onto crystalised dna and studying patterns
• Watson & Crick - made a model using knowledge of the base pairing that A and G matched the amount and C & T matched the same amount so A&T go together and C&G go together

Question 9

What is an enzyme ?

Answer 9

• A biological catalyst produced by living things to speed up useful chemical reactions in our body

Question 10

What is a catalyst ?

Answer 10

A catalyst is a substance which increase the speed of a reaction without being changed or used up in the reaction

Question 11

How do enzymes help in DNA replication?

Answer 11

Help copy a cells DNA before it divides by mitosis or meiosis

Question 12

How do enzymes help in Protein synthesis?

Answer 12

Enzymes hold amino acids in place and forms bonds between them

Question 13

How do enzymes help in digestion?

Answer 13

various enzymes are secreted into the gut to digest different food molecules

Question 14

How do enzymes catalyse reactions ?

Answer 14

• Has an active site where the substrate joins on to its substrate
• Only works with one substrate that fit sin the active site
• lock and key mechanism

Question 15

What is a mutation ?

Answer 15

A chnage in the organisms DNA base sequence

Whch coukd affect the sequence of amino acids in the portein which could affect the shape of the portein and its function.

They can either be Harmful, Beneficial of Neutral

Question 16

What is a harmful mutation ?

Answer 16

A mutation tha could cause a genetic disorder for example cystic fibrosis

Question 17

What is a Beneficial mutation ?

Answer 17

A mutation that could produce a new characteristic that is beneficial to an organism

e.g. bacteria can become resistnat to antibiotics

Question 18

What is a neutral mutation ?

Answer 18

Neither beneficial or harmful e.g. they don’t affect a proteins function

Question 19

What temperature do enzymes like and why ?

Answer 19

37 degrees celcius

More heat means more energy

Too hot and they will denature and bonds will break

Question 20

What pH do enzymes like and why ?

Answer 20

Works best at pH 7

some ezymes like pepsin work best at pH 2 - acidic conditons like in the stomach

Too high or low it will denature and chnage shape

Question 21

To get a faster reaction what do you have to do to the substrate concentraion and why ?

Answer 21

Increase the concentration as its more likely the enzyme will meet up and react with a substrate

Question 22

What is the human genome porject ?

Answer 22

Scientists from all over the world collaborate on the human genom eporject. The idea was to find every single human gene

Genes were found more quickly and data could be made public

Question 23

What are the advantages of the human genome project ?

Answer 23

1. Predict & prevent diseases
2. Develop better medicines
3. Accurate diagnosis (Know the genetic cause)
4. Improve forensic science (From DNA fingerprints find a suspect)
5. Gene therapy (cure genetic diseases)
6. Genetic disorders (test for mutations)

Question 24

What are the disadvantages of the Human genome project ?

Answer 24

• Increased stress - knowing they had or could get a disease
• gene-ism - poeple come under pressure not to have children
• Discrimination - hard/impossible to get insurance

Question 25

What is genetic engineering ?

Answer 25

Enzymes are used to cut and paste genes to produce genetically modified organisms.

Question 26

How does genetic engineering work ?

Answer 26

* A useful gene is cut out using enzymes * Enzymes are then used to cut another organisms chromosone and then insert the useful gene * E.g. Human genes can be used to make GM Bacteria

Question 27

How can genetic engneering benefit humans ?

Answer 27

* Reducing vitaming A definciency - In south Asia and africa. Golden rice is a GM rie that contains beta carotene which is used by our bodies to make vitamin A * Producing Human Insulin - Human insulin gene can be put into bacteria to produce human insulin, this can treat diabetes * Increasing crop yield - GM crops have had their genes modified to make them resistant to herbicides

Question 28

What are the worries with genetic engineering ?

Answer 28

1.