Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biology 1020 > DNA > Flashcards

DNA Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

Who produced the X-ray image of DNA that led Watson and Crick to think that DNA was double-helical?

A

Rosalind Franklin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

True or false: adenine and guanine both have a single-ring structure, and thymine and cytosine both have a double-ring structure.

A

False. The opposite is true for both sets.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Why does guanine only bond to cytosine?

A

Because they both have three spots for bonding, whereas adenine and cytosine only have two.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is DNA polymerase?

A

A category of molecules whose function is to add nucleotides to the 3’ end of DNA in replication. They also proofread and repair newly made DNA.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the origin of replication?

A

The site at which DNA replication begins.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

True or false: DNA is copied in sections beginning at several locations, and proceeding outward in both directions.

A

True. There are many origins of replication in one molecule.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is a replication fork?

A

The place where a DNA molecule is being opened up by helicase.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is RNA primer?

A

A short initial nucleotide sequence of 5-10 base pairs that serves as the starting point for the new DNA strand.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is a lagging strand? What is a leading strand?

A

The leading strand of DNA goes from 3’ to 5’ and can be replicated continuously. The lagging strand goes from 5’ to 3’, and consequently has to be replicated in chunks called Okazaki fragments.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Describe the difference between bacterial chromosomes and eukaryotic chromosomes.

A

Bacterial chromosomes are circular and associated with a small amount of protein. Eukaryotic chromosomes are linear and are associated with a large amount of protein.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Nucleosomes bundles DNA and histones at the second level of DNA packing. What are histones?

A

The proteins around which DNA is wound at the first level of DNA packing into chromatin.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is chromatin?

A

The complex of DNA and histones that makes up chromosomes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is DNA ligase?

A

An enzyme that joins the discontinuous fragments of the lagging strand during DNA replication.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is primase?

A

The enzyme that synthesizes RNA primers.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the two stages of protein synthesis?

A

Transcription and translation.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is transcription?

A

The synthesis of RNA under the direction of DNA.

17
Q

What is translation?

A

The synthesis of a polypeptide under the direction of mRNA.

18
Q

What is the difference between a prokaryotic cell’s protein synthesis and that of a eukaryotic cell?

A

A prokaryotic cell that has produced mRNA will immediately translate it without more processing. A eukaryotic cell has a nuclear envelope that separates transcription and translation, and RNA transcripts are modified and processed into finished mRNA.

19
Q

There are four nucleotide bases in DNA. How many amino acids are there?

A

20

20
Q

What is a codon?

A

A sequence of three nucleotides on an mRNA strand that codes for a specific amino acid. These are read in the 5’ to 3’ direction.

21
Q

True or false: mRNA has the same four bases as DNA.

A

False. mRNA uses uracil instead of thymine.

22
Q

What is a stop codon?

A

A codon that ends the synthesis of a polypeptide.

23
Q

Does a codon code for more than one amino acid?

A

No, each codon only codes for a particular amino acid. However, there is more than one codon that can code for each acid.

24
Q

True or false: every single organism uses the same chart of amino acids.

A

True. The genetic code is universal, which is why genes from different species can be inserted into other species.

25
Q

What are the three stages of RNA synthesis?

A

Initiation, elongation, and termination.

26
Q

What occurs during elongation of RNA synthesis?

A

RNA polymerase untwists DNA to expose the bases so that RNA bases can temporarily bind to them. After RNA polymerase moves on, the new (pre-)mRNA strand disconnects and the DNA strands bind together again.

27
Q

What is the difference between termination in bacteria and termination in eukaryotes?

A

In bacteria, RNA polymerase stops transcription at a terminator region. In eukaryotes, the RNA polymerase just falls off after the pre-mRNA is cut.

28
Q

How are RNA transcripts modified before leaving the nucleus?

A

They are spliced. This means that introns are cut out, and the exons are connected together. There is variation on which segments are treated as exons during RNA splicing. This does not occur in prokaryotes.)

29
Q

What is an intron?

A

A long, non-coding stretch of nucleotides that lies between coding regions, which are called exons (because they are EXpressed).

30
Q

What is the effect of alternative RNA splicing?

A

Some genes are able to encode more than one kind of polypeptide.

31
Q

What is tRNA?

A

Transfer RNA. There is one for each type of codon, and they bring amino acids to the ribosomes for polypeptide synthesis.

32
Q

How does termination work in eukaryotes?

A

A stop codon in the mRNA reaches the A site of the ribosome, and a release factor is accepted into the A site at the same time. The release factor hydrolyzes the bond between the polypeptide chain and the tRNA, causing the chain to float away from the P site. Everything proceeds to fall apart.

33
Q

True or false: polypeptide chains that have left the P site of the ribosome are immediately ready to function.

A

False. Often they need modification after translation.

34
Q

Are free ribosomes different than bound ribosomes?

A

Not very, but the free ribosomes tend to produce more proteins that function in the cytosol.

35
Q

What are the different kinds of mutations that can occur?

A

Substitutions, insertions, or deletions. Substitutions can lead to silent mutations, and the other two can lead to frameshift mutations. All of them can lead to missense or nonsense.

36
Q

What is a mutagen?

A

A physical or chemical agent that can cause mutations.

37
Q

What is a gene?

A

A region of DNA that can be expressed to produce a final functional product, either a polypeptide or an RNA molecule.

38
Q

What is a promoter in RNA synthesis?

A

A region of DNA that initiates transcription of a particular gene.

Biology 1020 (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions