Gene Expression

Question 1

What is a mutation

Answer 1

An alteration to the DNA base sequence that happens during DNA replication

Question 2

What are addition and deletion mutations?

Answer 2

Where one or more base is inserted or deleted from the DNA sequence

Question 3

What is a substitution mutation?

Answer 3

Where one base in the DNA sequence is replaced by another

Question 4

What is a duplication mutation?

Answer 4

Where one or more bases duplicate and repeat

Question 5

What is an inversion mutation?

Answer 5

Where a group of bases become separated from the DNA sequence, then rejoin in the reverse order

Question 6

What is a translocation mutation?

Answer 6

Where a group of bases get separated from the DNA sequence, and are then inserted into the DNA of a different chromosome

Question 7

Is a mutation resulting in a change to the amino acid sequence always harmful?

Answer 7

No, it may be neutral if the change in the protein has no effect. Could also be beneficial which helps natural selection

Question 8

What is a mutagenic agent? Give an example

Answer 8

Factors that increase the rate of gene mutation e.g alcohol and benzene

Question 9

What is a stem cell?

Answer 9

Undifferentiated cells, that can divide and turn into other specific cell types

Question 10

Totipotent cell definition

Answer 10

Can develop into any cell type including the placenta and embryo

Question 11

Pluripotent definition

Answer 11

Can develop into any cell type excluding the placenta and embryo

Question 12

Multipotent definition

Answer 12

Can only develop into a few different types of cell

Question 13

What happens to totipotent cells during embryonic development?

Answer 13

Certain parts of the DNA are translated so only some genes are switched on to differentiate the cell into a specific type

Question 14

Give one feature of pluripotent cells and the use of this feature

Answer 14

They can divide in unlimited numbers so can be used to repair or replace damaged tissue

Question 15

What is a unipotent cell? Give an example

Answer 15

A cell that can only develop into one type of cell, example is cardiomyocytes

Question 16

Which types of stem cell are found in embryos?

Answer 16

Totipotent and pluripotent

Question 17

Give some uses of stem cells

Answer 17

Bone marrow transplants, treating blood disorders, research

Question 18

What is a transcription factor?

Answer 18

A protein that controls the transcription of genes so that only certain parts of the DNA are expressed

Question 19

How do transcription factors work?

Answer 19

Bind to promoter region which makes it easier or more difficult for RNA polymerase to bind to the gene, this increases or decreases the rate of transcription

Question 20

What does epigenetics mean

Answer 20

A heritable change in gene function without change to the base sequence of DNA

Question 21

How does increased methylation of DNA affect gene transcription?

Answer 21

Adds a CH3 group to cytosine bases which prevents transcription factors from binding therefore gene transcription is suppressed

Question 22

How does decreased acetylation of histones affect gene transcription?

Answer 22

Decreasing acetylation increases positive charge of histones so binding becomes too tight and prevents transcription factors from accessing the DNA. Therefore gene transcription is suppressed

Question 23

How might epigenetic changes affect humans?

Answer 23

Could cause disease like cancer

Question 24

Characteristics of benign tumours

Answer 24

Slow growth, cells retain function and normal shape, easy to treat, don’t spread easily

Question 25

Characteristics of malignant tumours

Answer 25

Rapid uncontrolled growth, cells don’t retain function and often die, spreads easily and quickly, difficult to treat

Question 26

Describe the role of tumour-suppressor genes

Answer 26

Code for proteins that control cell division, stop cell division when the DNA is damaged

Question 27

Explain how tumour-suppressor genes can be involved in developing cancer

Answer 27

A mutation in a gene could code for a non functional protein. Increased methylation or decreased acetylation could prevent transcription. Cells will divide uncontrollably resulting in a tumour

Question 28

Describe the role of proto-oncogenes

Answer 28

Control cell division, code proteins that stimulate cell division

Question 29

Explain how proto-oncogenes can be involved in developing cancer

Answer 29

Mutation in a gene could turn it into a permanently activated oncogene. Decreased methylation or increased acetylation can cause excess transcription which results in uncontrolled cell division and the formation of a tumour

Question 30

Explain how abnormal methylation of genes can cause cancer

Answer 30

Hyper-methylation of tumour-suppressor genes or oncogenes can impair their function and cause the cell to divide uncontrollably

Question 31

Explain how oestrogen can be involved in developing breast cancer

Answer 31

Oestrogen is an activated of RNA polymerase, so in high oestrogen concentration areas, cell division can become uncontrolled

Question 32

What is a genome?

Answer 32

The complete set of genetic information contained in the cells of an organism

Question 33

What is genome sequencing?

Answer 33

Identifying the DNA base sequence of an individual, so we can determine the amino acid sequence of the polypeptides coded for by DNA

Question 34

What is the proteome?

Answer 34

The complete set of proteins in a cell

Question 35

Applications of genome sequencing:

Answer 35

Genetic matching, personalised medicine, synthetic biology

Question 36

How have sequencing methods changed over time?

Answer 36

Used to be a manual process but is now more automated