1 The Human Genome

Question 1

What does genome consist of

Answer 1

All DNA in a cell - includes introns and exons

Question 2

What is an exon in DNA

Answer 2

Section that codes for proteins

Question 3

How many nucleotides are there in the human genome

Answer 3

3 x 10^9

Question 4

How many autosomes do humans have

Answer 4

44

Question 5

How many sex chromosomes do humans have

Answer 5

2

Question 6

Which cells doesn’t have a nucleus and why

Answer 6

RBC- increases O2 capacity and can squeeze through capillaries
Platelets

Question 7

What is Synteny

Answer 7

When genes are present in the same order across species

Question 8

What is a Barr body

Answer 8

In inactive X chromosome

Women inactivate one copy of thier X chromosome and push it to the edge of the nucleus

Question 9

How many chromosomes do chimps and gorillas have

Answer 9

48 chromosomes

Question 10

What is human chromosome number 2 a fusion of?

Answer 10

Two chimp/ gorilla chromosomes

Question 11

What is Translocation and what can it cause

Answer 11

When chromosome segments change location

• break off and reattach to a new chromosome
• can cause disease and cancer

Question 12

Give examples of cells which can copy DNA by dividing the nucleus but not entire cell

Answer 12

Hepatocytes

Megakaryocytes

Question 13

Translocation in chromosome 9 and 22 = Philadelphia chromosome leads to what type of cancer

Answer 13

Chronic myelogenous leukaemia = bone marrow produces too many myeloid cells that aren’t fully myeloid cells that are not fully developed

Question 14

What are the two types of regularity RNAs

Answer 14

MRNA AND Xist

Question 15

What are they two types of structural RNAs

Answer 15

RRNA tRNA

Question 16

What is Xist

Answer 16

X inactivation Specific Transcript

In XX cells one copy of X chromosome is switched off

Question 17

What does Xist do

Answer 17

Binds to X chromosome in females which condenses and inactivates them so women only receive info from one chromosome

Question 18

Maimoona is the best

Answer 18

Yayyy

Question 19

What does each end of mRNA contain

Answer 19

Untranslated regions UTR
5’ UTR= important for regulation of translation
3’ UTR= section of mRNA that immediately follows translation termination codon

Question 20

What are gene deserts

Answer 20

Large non-coding (intergenic) regions

Question 21

Genomic imprinting

Answer 21

Allows genes to be expressed differently depending on which parents they come from

Question 22

What is the result of imprinting in diploid organisms

Answer 22

One of two alleles is silenced

Question 23

Which two ways can genes be silenced by

Answer 23

DNA methylation or histone modification

Question 24

Retrovirus

Answer 24

RNA viruses that insert their DNA into the DNA of host cells

Question 25

Give an example of a retrovirus

Answer 25

HIV

Question 26

How much space does mutated retrovirus take up in our DNA compared to exons

Answer 26

Twice as much

Question 27

What is a pseudo gene

Answer 27

An allele of normal genes that have become non functional due to mutations.

Question 28

Give an example of how pseudo genes might be generated

Answer 28

Gene duplication - if genes are inserted unintentionally it becomes a non functional gene - no protein Or Protein codon region may contain stop codon = non functional protein

Question 29

Why are stop codons also pseudogenes

Answer 29

They lack protein-coding ability

Question 30

What are VNTRs

Answer 30

Variable number tendon regions - multiple copies of short sequences

Question 31

What is slippage caused by and what can it cause

Answer 31

Caused by insertion of two many or too few copies | Leads to disease

Question 32

Give an example of a disease caused by slippage of replication of repeat sequence

Answer 32

Huntington’s disease

Question 33

What is Huntington’s disease caused by

Answer 33

Expansion of CAG repeat in Huntington protein gene- causes Neuron degeneration

Question 34

Symptoms of Huntington’s disease

Answer 34

Death of neurons - affects balance movement, talking breathing etc

Question 35

What is a telomere and what is their function

Answer 35

Repeat sequence in a genome | Protects the end of chromosomes from deterioration/ fusion with neighbouring chromosomes

Question 36

What is the repeat sequence of a telomere

Answer 36

TTAGGG

Question 37

Which enzyme builds telomeres

Answer 37

Telomerase

Question 38

Which cells switch on telomerase

Answer 38

Stem cells

Question 39

Which cells switch off telomerase

Answer 39

Differentiated cells

Question 40

Another function of telomeres

Answer 40

Regulate number of cell divisions

Question 41

What is cell senescence

Answer 41

When it can no longer divide/ Inactive

Question 42

What effect do cancer cells have on telomerase

Answer 42

Increase telomerase, adding more repeat sequences so cells can continuously divide

Question 43

What is a SNP single nucleotide polymorphism

Answer 43

DNA sequence variation occurring commonly within a | population (e.g. 1%) in which a single nucleotide in genome differs between members of species

Question 44

What effect do SNPs have on ANRIL

Answer 44

) increases risk of heart disease & | diabetes

Question 45

Do all SNPs cause changes in phenotype

Answer 45

Some do but some are silent