Biology Chapter 3 Chromosomes and Genes

Question 1

What is the genome

Answer 1

All the genetic material of an organism

Question 2

What do chromosomes come in

Answer 2

Pairs

Question 3

What is found on chromosomes

Answer 3

Genes

Question 4

What are genes made up of

Answer 4

DNA

Question 5

What shape is DNA

Answer 5

A Double Helix

Question 6

What is the term for different forms of the same gene

Answer 6

Allele
eg blue eyes, green eyes, brown eyes

Question 7

What type of allele is expressed even if only one of the pair is of this type

Answer 7

Dominant allele

Question 8

What is the term used to describe the type of allele that must be present in both in order to be expressed - is written as a small letter

Answer 8

Recessive

Question 9

What is the term used to describe having one dominant and one recessive allele e.g. Bb

Answer 9

Heterozygous

Question 10

What is the term used to describe having both alleles the same eg bb or BB

Answer 10

Homozygous

Question 11

What is the term used to describe the genetic makeup of an individual eg DD od Dd

Answer 11

Genotype

Question 12

What is meant by the term phenotype

Answer 12

The features the person has because of their genotype

Question 13

If both parents are heterozygous e.g Bb what will the offspring be

Answer 13

Both parents Bb
Gametes either B or b
Draw a genetic diagram (Punnet square) to show the result
B b
B BB Bb
b Bb bb
Genotype - 1BB, 2 Bb, 1bb
25% chance have recessive characteristic (bb)
50% heterozygous (Bb)
25% homozygous dominant (BB)

Question 14

In a pedigree diagram what does it show

Answer 14

Shows link between different family members - you need to be able to read keys on a pedigree diagram and work out genotypes

Question 15

What is a mutation

Answer 15

A random change in DNA or chromosomes

Question 16

What is cancer

Answer 16

Uncontrolled cell division

Question 17

What can cause skin cancer

Answer 17

UV light

Question 18

Name 2 examples of genetic conditions

Answer 18

Down’s syndrome
Cystic Fibrosis

Question 19

How would the chromosomes of a person with Downs syndrome be different

Answer 19

They have 47 chromosomes instead of 46
They have an extra chromosome on pair 21

Question 20

What is genetic screening

Answer 20

A process used to see if a person is carrying a certain genetic condition

Question 21

What is the name of the procedure used to check a foetal cells to see if the foetus has Downs syndrome

Answer 21

Amniocentesis
- risk of miscarriage with this procedure

Question 22

What are the ethical concerns with amniocentesis

Answer 22

Person has to decide what to do with the results - do they keep the child or have an abortion

Question 23

What is genetic engineering

Answer 23

Modification of DNA by inserting gene from another organism

Question 24

Insulin is made by genetically engineered bacteria
What are the advantages of this

Answer 24

Can produce large amounts
Produces human insulin so is compatible to person (other animal insulin is slightly different)

Question 25

Insulin is made by genetically engineered bacteria
What are the disadvantages of this

Answer 25

moral issue - some people think it is not right to alter organisms DNA
May be other unforseen outcomes from modification
what is the GM material getis into the wild?