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Molecular Biology > Ch. 4 Content of the Genome (Exam 1) > Flashcards

Ch. 4 Content of the Genome (Exam 1) Flashcards

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1
Q

Define genome.

A

Entire DNA content of cell and all genes in an organism

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2
Q

Define gene.

A

Short section of DNA acting as instructions to make proteins

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3
Q

Why can’t genes solely be defined as DNA sequences that encode a polypeptide (HINT: 2 reasons, RNA, polypeptides)?

A

1) Many genes encode multiple polypeptides
2) Many genes encode RNAs that serve other functions (aside from mRNA)

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4
Q

Seeing that the gene is transcribed into a functional RNA molecule, the gene is a unit of…

A

Transcription

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5
Q

In what are the 4 stages that genes can be categorized?

A

1) Genome
2) Transcriptome
3) Proteome
4) Interactome

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6
Q

Define transcriptome.

A

The full range of mRNA molecules expressed by an organism

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7
Q

Define proteome.

A

Complete set of polypeptides encoded by whole genome or produced in particular cell or tissue

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8
Q

What structures in the transcriptome should the proteome correspond to?

A

The mRNAs

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9
Q

Define interactome.

A

Protein-protein interactions in a multiprotein or multimolecular complex

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10
Q

How do open reading frames (ORFs) help maximize the number of polypeptide-encoding genes in the genome?

A

By seeing that genes are present and functional

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11
Q

What is the best way to determine if a gene is essential or not?

A

By examining the phenotypic effect of a null mutation on that gene

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12
Q

Aside from the null mutation method, what is another way of determining if a gene is essential?

A

Looking for redundant genes that will serve as a backup to the OG to produce the associated protein in the absence of the OG gene

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13
Q

In what 2 ways is sequencing DNA of the genome helpful?

A

1) Helps us ID genes
2) Indicates distance between said genes

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14
Q

What result did the human genome project find regarding the existence of alleles?

A

There are multiple alleles for one gene, and each has a different phenotypic effect

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15
Q

Define polymorphism.

A

Coexistence of multiple alleles in a population locus

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16
Q

What is the most common polymorphism?

A

Single nucleotide polymorphism (SNP)

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17
Q

Define single nucleotide polymorphism.

A

Genetic variation in a single nucleotide

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18
Q

Define nonrepetitive DNA.

A

Unique sequences with only one copy in a haploid genome

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19
Q

Define repetitive DNA.

A

Sequences present in more than one copy in each haploid genome

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20
Q

Define moderately repetitive DNA.

A

Relatively short repeating DNA sequence

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21
Q

Define highly repetitive DNA.

A

Very, very short repeating DNA sequence

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22
Q

What is a better indication of coding potential than genome size?

A

The amount of nonrepetitive DNA seeing that mRNA is transcribed from it

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23
Q

Why do highly repetitive sequences reanneal so quickly compared to nonrepetitive, single-copy sequences?

A

Because so many copies exist, and they are not very complex compared to single-copy sequences

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24
Q

What type of genomic sequence do prokaryotes almost exclusively contain?

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A

Nonrepetitive DNA

25
In animal cells, up to half of all DNA is represented by what 2 genomic sub-sequences?
Moderately and highly repetitive sequences
26
Where can most of the eukaryotic genome be found?
In the nucleus
27
What will highly repetitive sequences typically be repeated as?
Tandem repeats
28
Both mitochondria and chloroplasts contain genomes with functional genes. What type of inheritance is this indicative of?
Non-Mendelian inheritance
29
Define non-Mendelian inheritance.
Failure of offspring to display Mendelian segregation for parental traits, indicating that genes outside the nucleus aren't distributed to gametes
30
What is the shape of most organelle genomes?
Circular
31
Why are organelle genomes considered to be repetitive sequences?
Because there are several copies of the genome in the organelle itself, and there are multiple organelles per cell
32
Does the relative amount of protein-coding genes in mitochondria correlate to the genome size?
No. The total number of protein-coding genes is quite small and does not correlate
33
Some proteins found in mitochondria are coded by the mitochondria itself, but others are coded in the...
Nucleus
34
How are mitochondrial proteins that are coded by the nucleus get to the mitochondria (HINT: 2 parts)?
They are first synthesized in the cytoplasm and then transported into the organelle
35
If the cell has mechanisms for transporting proteins into mitochondria and chloroplasts, then why not have all the organelle proteins specified by the nuclear genome?
Some organelle proteins are so hydrophobic that they cannot pass through the organelle membranes, so they are made in-house
36
What is the explanation for why mitochondria and chloroplasts contain their own genetic information?
Endosymbiotic theory
37
According to the endosymbiotic theory, mitochondria hail from...
A bacterium that was captured within a eukaryotic cell
38
According to the endosymbiotic theory, what do chloroplasts hail from?
Cyanobacteria
39
What are the 2 main impacts that endosymbiosis had on mitochondria and chloroplasts?
1) These organelles have lost many gene functions necessary for independent living 2) Many genes encoding organelle functions were transferred to the nucleus
40
What is the bare minimum amount of genes needed for a cell to be functional?
At least 500
41
In prokaryotic genomes, the genome size directly correlates to the...
Number of genes present
42
Describe the correlation between genome size and gene number in eukaryotic genomes compared to prokaryotic genomes.
Much weaker than in prokaryotes. Bigger genome does not mean more genes.
43
Define plasmid.
An independent, smaller, circular DNA molecule carrying additional genes
44
In what two ways are plasmids advantageous to prokaryotes?
1) Antibiotic resistance 2) Use of toluene as a carbon source
45
What is meant when we say that plasmids are indispensable?
Prokaryotes can still exist without them, but survival and reproduction are more difficult
46
What do we mean when we say that plasmids are copied independently?
Every plasmid has its own origin of replication
47
Why is it important that each plasmid has its own origin of replication?
To ensure that the plasmids get replicated and copied by the host bacterium
48
Why are there no introns in the genes of prokaryotic organisms?
Because they are comprised almost exclusively of nonrepetitive DNA sequences
49
In the eukaryotic genome, where are the linear DNA molecules contained?
Chromosomes within the nucleus
50
In eukaryotic organisms, where will you find the small, circular genome?
Mitochondria
51
In eukaryotic genomes, the genome size broadly coincides with...
Organism complexity
52
Why is the genetic organization of the yeast genome more economical than it is in higher eukaryotes?
Yeast genes are packed much more closely, which saves space, and allows for the genome to accommodate many genes
53
What do larger genomes tend to have high copy numbers of?
Repeated sequences
54
How much of the human genome consists of exons (HINT: percentage)?
1%
55
What percentage of the human genome do repeated sequences account for?
50%
56
How often do SNPs occur?
Approximately every 1000 bases
57
How many times will a moderately repeating DNA sequence appear in the genome?
10 to 1000 times
58
How many times will a highly repetitive DNA sequence appear in the genome?
Many thousand times
59
How long (in bp) are highly repetitive DNA sequences typically?
100 bp

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