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Molecular Biology > Ch. 3 The Interrupted Gene (Exam 1) > Flashcards

Ch. 3 The Interrupted Gene (Exam 1) Flashcards

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1
Q

Define exon.

A

Sequence in DNA that codes for amino acid sequences

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2
Q

Define intron.

A

Sequence in DNA that does not translate into protein

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3
Q

How are interrupted genes expressed?

A

Via pre-mRNA

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4
Q

Why are interrupted genes longer than mature mRNA?

A

Introns are spread throughout interrupted genes

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5
Q

What is the basis of RNA splicing?

A

Removing introns and splicing the remaining exons together

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6
Q

What does alternative splicing produce?

A

Variant proteins from one gene in a eukaryotic cell

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7
Q

What regulates alternative splicing?

A

Introns

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8
Q

What regulates gene expression and DNA initiation?

A

Introns

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9
Q

Why is the correspondence between gene and polypeptide maintained after splicing?

A

The exon order does not change between DNA and RNA

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10
Q

What defines the length of a gene?

A

The pre-mRNA, which contains introns

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11
Q

How do mutations in exons directly affect polypeptides?

A

Exons code for polypeptides, and a change in the exon will lead to some sort of mutation

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12
Q

How do mutations in introns indirectly affect polypeptide production?

A

They affect mRNA production by halting exon splicing, which is typically deleterious

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13
Q

What is the most common outcome of an intron mutation?

A

A shortened polypeptide sequence

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14
Q

Define complementary DNA (cDNA).

A

DNA corresponding to the OG sequence, with the restriction sites on exons included

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15
Q

Why is it that exon similarity is conserved but intron similarity isn’t?

A

Introns are not bound by any selective pressure to produce useful polypeptide sequences

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16
Q

Exons and introns mutate at the same rate, but exons…

A

Are selectively eliminated more often

17
Q

Where is intron position conserved?

A

Homologous genes compared across different organisms

18
Q

Overall gene length is determined by…

A

Introns

19
Q

What do alternate initiation & termination codons allow?

A

Multiple variants of a polypeptide chain

20
Q

What happens when mRNA is read from different reading frames?

A

Different polypeptide sequences are produced from the same DNA sequence

21
Q

Having 2 alternate start codons in a single sequences can produce…

A

A short or full-length polypeptide

22
Q

Under what condition can a sequence successfully translate a polypeptide?

A

As long as the gene section being translated is functional

23
Q

Define overlapping gene (HINT: include reading frame).

A

A gene that uses more than one reading frame, which means that part of a nucleotide sequence overlaps with another

24
Q

Overlapping genes encode 2 { } proteins.

A

Nonhomologous

25
Q

What splicing mechanism creates homologous proteins?

A

Alternative splicing

26
Q

How do homologous proteins differ?

A

By presence or absence of certain regions

27
Q

What two ways does alternative splicing do its job?

A

1) Including/excluding individual exons
2) Choosing between alternate exons

28
Q

The gene sequence that makes a specific protein is based on how many potential reading frames?

A

3

29
Q

How does alternate splicing affect protein?

A

The translated amino acid sequence and overall function will differ

30
Q

How does alternative splicing benefit eukaryotes?

A

Increasing protein biodiversity

31
Q

What type of mutations do introns accumulate over time?

A

Point substitutions

32
Q

Define protein domain.

A

Distinct functional and/or structural unit of protein

33
Q

How are exons associated with protein domains?

A

Because they encode polypeptide sequences with certain functions

34
Q

The exons of some genes appearing to be homologous to the exons of others is indicative of…

A

Common ancestry of the functional domain

35
Q

What does a common feature in a set of genes identify?

A

Some shared property proceeding their evolutionary separation

36
Q

Define gene family.

A

Gene group encoding related or identical products resulting from gene duplication events (e.g. globin genes having similar organization)

37
Q

The exon structure of globin genes corresponds to…

A

Protein function

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