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Genetics > Exam 3 - Q's > Flashcards

Exam 3 - Q's Flashcards

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1
Q

How do hydrogen bonds differ from covalent bonds?

A

Hydrogen bonds are weak and bind hydrogen and another atom while covalent bonds are strong result from electron sharing between atoms

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2
Q

When a molecule is described as “highly evolutionary conserved”, what is meant?

A

It means that the molecule has remained essentially unchanged through evolution

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3
Q

What conclusion about molecular function do biologists draw from the fact of a high degree conservation of molecular structure and/or gene sequence?

A

We all come from one common ancestor

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4
Q

What does DNA polymerase do?

A

An enzyme that reads the nucleotide sequence of the template strand and inserts complementary nucleotides in a 5’ to 3’ direction

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5
Q

What 3’ and 5’ refer to and why do we use these terms?

A

DNA replication goes from 5’ to 3’. The deoxyribose sugar consists of 1-5, and DNA connects from 5-3

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6
Q

How does a chromosome differ from a strand of DNA?

A

A chromosome consists of a single DNA strand tightly curled up between protein molecules (histone)

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7
Q

What are the differences between DNA and RNA?

A
  • DNA is double stranded, RNA single
  • DNA sugar: deoxyribose
  • RNA sugar: ribose
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8
Q

What are the base pairing rules for DNA?

A

A-T, G-C

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9
Q

What are the base pairing rules for RNA?

A

A-U, G-C

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10
Q

What are the 4 bases of RNA?

A

CUAG, cytosine, uracil, adenine, guanine

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11
Q

What are the 4 bases of DNA?

A

CTAG, cytosine, thymine, adenine, guanine

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12
Q

What did Watson and Crick receive the Nobel Prize for?

A

solving the structure of DNA

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13
Q

How does a cell turn a DNA sequence into a functional protein?

A

Information goes from DNA to mRNA in codons. DNA > transcription (DNA template +RNA strand = mRNA) > translation (tRNA codons bind to complementary codons in mRNA, ribosome moves along mRNA linking amino acids and producing a polypeptide chain) > termination (functional protein)

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14
Q

What is the difference between an intron and an exon?

A

Introns are DNA sequences removed during processing while exons are DNA sequences joined to other exons and are translated into the amino acid sequence of a protein

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15
Q

What happens to introns and exons as pre-mRNA is processed?

A

Introns are removed to connect exons with other exons

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16
Q

What are the functions of start and stop codons and where do they occur?

A

Start codons signal where for mRNA to start translating. Stop codons stop this process.

17
Q

What are the only stop codons? Does it have any other functions?

A

UAA, UAG, UGA. No

18
Q

What is the only start codon? Does it have other functions?

A

AUG. Yes it codes for the amino acid methionine

19
Q

What are the similarities and differences of the 20 different amino acids?

A

All amino acids have a central C atom with an H bound to it. Each amino acid has a different R group

20
Q

What do we mean by “levels of structure” for a protein? What is the primary structure and how does this relate to the DNA and mRNA sequence?

A

How many times the protein folds itself and how it does. The primary structure is just the amino acid sequence of a polypeptide. To get to higher levels the amino acids interact with each other

21
Q

What is the difference between a polypeptide and a protein?

A

A polypeptide is a linear polymer of amino acids. A protein contains one or more of these

22
Q

Why are enzymes needed in metabolic pathways?

A

Enzymes convert substrates into products by catalyzing chemical reactions

23
Q

How can a single mutant enzyme in a metabolic pathway produce pleiotropic effects?

A

If a mutant enzyme prevents a reaction from happening, all reactions after that are now blocked.

24
Q

Do all blocks in metabolic pathways lead to equally severe effects?

A

No

25
Q

Why is early detection of galactosemia important?

A

Because if the new born is fed galactose in the first few days, the child will become retarded beyond repair. If treated early the symptoms can be reversed

26
Q

Can genetic defects in proteins other than enzymes change phenotype?

A

Yes hemoglobin

27
Q

Are the effects of drugs independent of genotype?

A

No, drugs affect people differently because of different genes

28
Q

How do mutations in somatic cells differ from germ line mutations?

A

Somatic cell mutations are mutations that occur in cells that do not form gametes. Mutation cannot be transmitted to future generations. Germ line mutations occur in cells that produce gametes, and these mutations will be passed on to offspring

29
Q

How do mutations actually happen?

A

Mutations can occur spontaneously as a result of errors in DNA replication or by exposure to radiations or chemicals

30
Q

Are most mutations deleterious, helpful, or neutral?

A

Neither because a mutation can be harmful or helpful based on the environment

31
Q

What is trinucleotide repeat?

A

Genes that contain short nucleotide sequences that repeat often. the greater the amount of repeats the more severe the effect

32
Q

Why are multiple DNA repair enzymes necessary? What would happen if one of these systems had a germ line mutation?

A

Because the repair enzymes can become mutated and these need to be repaired somehow. If one of these was germ line, the offspring would have DNA repair enzyme problems

33
Q

How does cancer start?

A

A single mutation in a single cell

34
Q

Why do most cancers take so long to become a problem?

A

Because cancers rely on multiple mutations across multiple genes and that takes time

35
Q

How does the 2-hit hypothesis relate mutations that are recessive at the cellular level to a familial inheritance pattern that is dominant with incomplete penetrance?

A

It has to have the 2nd mutation in order to have an effect

36
Q

What is the normal function of tumor suppressor genes?

A

They are proteins that stop cell division

37
Q

What is the normal function of a proto-oncogene?

A

They are genes that maintain or initiate cell division and may become cancerous

38
Q

Why do mutations in genes involved in DNA repair make cancer a more likely outcome?

A

If mistakes in DNA go unchanged and are tumor suppressor genes or proto-suppressor genes, eventually uncontrolled cell division ensues

Genetics (6 decks)

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