Bio Lect 9

Question 1

What is the approximate number of base pairs in Escherichia coli DNA?

Answer 1

5 × 10^6 base pairs

Question 2

How quickly can the DNA of Escherichia coli be copied?

Answer 2

Within about 30 min (3000 base pairs per second)

Question 3

What is the error rate of DNA replication?

Answer 3

About 1 in 10^9 base pairs

Question 4

What process is supplemented by specific base-pairing in DNA replication?

Answer 4

Proof-reading

Question 5

Which enzymes have proof-reading ability during DNA replication?

Answer 5

All DNA polymerases

Question 6

What can damage DNA?

Answer 6

High energy radiation (e.g. UV, X-ray) and chemicals (mutagens)

Question 7

How do mutagens affect DNA?

Answer 7

Increase the rate of mutations and can lead to altered proteins

Question 8

How many enzymes can detect and repair DNA damage?

Answer 8

More than 100 enzymes

Question 9

What is one example of a DNA repair mechanism?

Answer 9

Nucleotide excision repair

Question 10

What type of damage does nucleotide excision repair typically address?

Answer 10

Thymidine dimer formed by UV radiation

Question 11

What occurs first in the repair of a thymine dimer?

Answer 11

A nuclease enzyme cuts the damaged DNA strand at two points

Question 12

What happens after the damaged section of DNA is removed?

Answer 12

Repair synthesis by a DNA polymerase fills in the missing nucleotides

Question 13

What is the final step in DNA repair after synthesis?

Answer 13

DNA ligase seals the free end of the new DNA to the old DNA

Question 14

Fill in the blank: The error rate of DNA replication is approximately 1 in _______.

Answer 14

10^9

Question 15

True or False: DNA polymerases are responsible for detecting and removing incorrectly added bases.

Answer 15

True

Question 16

How much DNA is there in a human cell?

Answer 16

Human DNA contains 3 x 10^9 base pairs

This measurement refers to the total base pairs present in the human genome.

Question 17

If stretched out, how much DNA would there be per cell?

Answer 17

About 1 metre of DNA per cell

This is based on the length of the DNA when fully extended.

Question 18

What is the abbreviation for mitochondrial DNA?

Answer 18

mtDNA

Question 19

In which part of the cell is mitochondrial DNA (mtDNA) found?

Answer 19

Near mitochondrial membrane

Question 20

What is the structure of mitochondrial DNA?

Answer 20

Double stranded and circular

Question 21

How many genes does mitochondrial DNA code for?

Answer 21

37 genes

Question 22

What is the primary function of the proteins coded by mtDNA?

Answer 22

In respiratory chain

Question 23

How is mitochondrial DNA inherited?

Answer 23

Via maternal lineage

Question 24

True or False: Mitochondrial DNA is mixed between maternal and paternal lineage.

Answer 24

False

Question 25

What year was mitochondrial DNA discovered?

Answer 25

1963

Question 26

What type of diseases can mutations in mtDNA cause?

Answer 26

Over 40 different diseases

Question 27

What is a common feature of diseases caused by mtDNA mutations?

Answer 27

Inability to generate enough energy

Question 28

Mitochondrial DNA is useful for analyzing which aspects of family history?

Answer 28

Mother's family history, ethnicity, migration

Question 29

Who suggested the link between genes and proteins?

Answer 29

Sir Archibald Garrod ## Footnote Garrod's work in 1909 focused on inherited diseases and coined the term 'inborn errors of metabolism'.

Question 30

What term did Garrod coin related to inherited diseases?

Answer 30

'Inborn errors of metabolism' ## Footnote This term describes conditions where a person cannot produce a specific protein or enzyme.

Question 31

What was the significance of Garrod's research?

Answer 31

Linked symptoms of inherited diseases with protein synthesis issues ## Footnote He was the first to recognize Mendel's laws in humans.

Question 32

What organism did Beadle and Tatum study to explore gene functions?

Answer 32

Neurospora crassa ## Footnote This bread mould is a good model organism as it can grow on simple media and synthesize its own amino acids.

Question 33

What hypothesis did Beadle and Tatum propose?

Answer 33

'One gene-one enzyme' hypothesis ## Footnote This hypothesis suggests that each gene is responsible for the production of a specific enzyme.

Question 34

What did Beadle and Tatum use to study mutations?

Answer 34

X-rays ## Footnote They produced mutants of Neurospora crassa using X-rays to investigate the arginine synthesis pathway.

Question 35

What amino acid was studied by Beadle and Tatum in their research?

Answer 35

Arginine ## Footnote Arginine is an amino acid that plays a crucial role in the synthesis pathways studied.

Question 36

What did Edward Tatum contribute to the field of genetics?

Answer 36

Co-author of the 'One gene-one enzyme' hypothesis with Beadle ## Footnote Tatum's work focused on the biochemical aspects of genetics.

Question 37

What was the Nobel Prize awarded to Beadle and Tatum for?

Answer 37

Their research on gene regulation of chemical events ## Footnote Awarded in 1958, it recognized their contributions to understanding the molecular basis of genetics.

Question 38

True or False: Garrod was the first to recognize Mendel's laws in animals.

Answer 38

False ## Footnote Garrod recognized Mendel's laws in humans.