Cell Biology

Question 1

What is a genome?

Answer 1

complete collection of genetic material within an organism

Question 2

What is genomics?

Answer 2

DNA structure of genes and their localisation within the genome

Question 3

What is protenomics?

Answer 3

characterisation of biological processes from measurement of protein expression localisation and post translational modification

Question 4

Describe the human genome

Answer 4

-sequences in 2003, 10% of DNA in mammals encodes genome
-repeating sequences
-3 billion base pairs
-30,000 genes

Question 5

What is pharmacogenomics?

Answer 5

effects of chemicals on gene transcription and protein expression

Question 6

What can profiling an individuals genome (sequencing) do?

Answer 6

-understand inherited basis for congenital disorders
-predict our chance of developing certain diseases

Question 7

What are the 2 types of mutations?

Answer 7

-germline
-somatic

Question 8

Describe germline mutations

Answer 8

gonadal cells that become eggs/sperm carrying the mutation within their DNA

Question 9

Describe somatic mutation

Answer 9

-cells of body carrying a mutation
-underlies monogenic disorders- disorders controlled by a single gene

Question 10

What are the different types of genetic disorders?

Answer 10

-single gene disorders
-chromosomal disorders
-polygenic disorders
-somatic disorders

Question 11

What is a single gene disorder?

Answer 11

mutation in a single gene e.g. cystic fibrosis

Question 12

What is a chromosomal disorder?

Answer 12

change, gain, loss or exchange of chromosome elements e.g. downs syndrome

Question 13

What is a polygenic disorder?

Answer 13

combined effects of mutations in multiple gene or in combination with environmental factors e.g. natural tube defects

Question 14

What is a somatic disorder?

Answer 14

non-germline disorder such as uncontrolled growth e.g. cancer

Question 15

Describe the molecular structure of DNA

Answer 15

-double helix=compact structure
-DNA length shortened by interaction w/ histone proteins
-HP contains AA’s arginine and lysine (+ charged, pH 7.4)
- so - charge phosphate groups on DNA more attracted to arginine residues than lysine

Question 16

Describe histone H1

Answer 16

-globular (NH2) and arm (COOH) domains
-H1 binds to nucleosome via globular domain
-the arm domain binds to other H1 globular domains

Question 17

Describe chromosomes

Answer 17

-genetic info stored within DNA
-blueprint for human proteome
-genes located on chromosome

Question 18

Describe somatic cells

Answer 18

-46 chromosomes (diploid)
-22 autosomal pairs
-one from each parent
-2 gender chromosomes

Question 19

Describe chromosome 1

Answer 19

-largest
-250 mega bases of DNA

Question 20

Describe chromosome 2

Answer 20

240 Mb of DNA

Question 21

Describe chromosome 21 + 22

Answer 21

55 + 60 Mb of DNA

Question 22

Describe the X + Y chromosome

Answer 22

140 Mb of DNA (X)+ 60Mb DNA (Y)

Question 23

Describe the female XX chromosome

Answer 23

-only one is transcriptionally active (lyonisation)
-avoids 2 copies X transmitted gene products
-methylation of X chromosome inactivates the same chromosome

Question 24

What is chromosome karotyping?

Answer 24

-visual inspection of chromosomes in metaphase
-use spindle toxins e.g. colchicine

Question 25

Describe the centromere of a chromosome

Answer 25

-middle (metacentric)
-towards one end (acrocentric): shorter arm= p arm, longer arm= q arm

Question 26

What are the stripes that appear on stained chromosomes?

Answer 26

-dark bands: tightly coiled chromatin= transcriptionally inactive
-clear bands: not so tightly coiled euchromatin transcriptionally active

Question 27

What are the different types of chromosome abnormalities?

Answer 27

number + structure

Question 28

What are the different types of number abnormalities?

Answer 28

-polyploidy
-aneuploidy
-monosomy
-trisomy

Question 29

Describe the polyploidy number abnormality

Answer 29

-additional set of chromosomes
-multiples of 23

Question 30

Describe the aneuploidy number abnormality

Answer 30

-missing set of chromosomes
-multiples of 23
-not compatible with life

Question 31

Describe the monosomy number abnormality

Answer 31

-only one copy of a chromosome in diploid cell
-rarely compatible with life

Question 32

Describe the trisomy number abnormality

Answer 32

-3 copies of a chromosome in diploid cell
-trisomy 21 (downs syndrome)= most common

Question 33

What are the 3 types of structure abnormalities?

Answer 33

-duplications
-inversions
-isochromosome
-translocations
-deletions

Question 34

Describe the duplication structure abnormality

Answer 34

unequal crossover

Question 35

Describe the inversion structure abnormality

Answer 35

-2 breaks in chromosome, free portion rotates
-involves centromere= pericentric
-not involve centromere= paracentric
-can cause haemophilia

Question 36

Describe the isochromosome structure abnormality

Answer 36

-form after chromosome pairs split during telophase
-new chromosomes have only short/long arms

Question 37

Describe the translocation structure abnormality

Answer 37

-exchange of genetic material between chromosomes = reciprocal translocation
-short p arms of chromosomes are long and long q arms fuse to form one large chromosome

Question 38

Describe the deletion structure abnormality

Answer 38

-loss of genetic material when breaks in chromosomes occur
-e.g. cri-du-chat syndrome= child’s distinctive cry, partial loss of chromosome 5 p arms

Question 39

What are telomeres?

Answer 39

-end of each chromosome, non coding
-copies of hexameric nucleotides
-shorten with cell age

Question 40

What do telomeres maintain/promote?

Answer 40

-chromosome stability
-complete DNA replication
-aid chromosome pairing