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AP BIO > Unit 6 > Flashcards

Unit 6 Flashcards

1
Q

In the early 1900’s what two things did scientists decide chromosomes were made of?

A

-DNA and protein

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2
Q

Originally, what molecule did scientists think was the hereditary material in the nucleus? Why?

A

-protein because it was more complex and built of many more amino acids (dna-4 and protein 20)

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3
Q

Explain Fredrick Griffith’s transformation experiment in 1928.

A

Griffing heat killed S cells and mixed them with living R cells that caused the mouse to die. Something in this mix was being transferred to the R cells to kill the mouse. Independently the R cells and the heat killed S cells did not kill the mouse but the alive S cells did.

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4
Q

In 1944, Avery, McCarty and McLeod announced the transforming factor in Griffith’s experiment was _________.

A

DNA

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5
Q

Hershey and Chase worked with bacteriophages. What is a bacteriophage? What were they testing in their experiment?

A

Bacteriophages are viruses that infect bacteria
-They were testing that DNA is the genetic material of a phage(bacteriophage)
(whether phages work by transmitting their DNA or protein)

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6
Q

Why was it important the DNA was tagged with phosphorus and the protein was tagged with sulfur?

A

DNA has phosphorus and does not have sulfur

Protein has sulfur but not phosphorus

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7
Q

What were Erwin Chargaff’s findings? Why were his findings significant in the structure of DNA?

A
  • purines and pyramids go together
  • percentage of Adenine equal to thymine (A and T are equal) (C and G are equal)
  • DNA composition varies from one species to the next
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8
Q

What is Rosalind Franklin known for? How was this significant to the structure of DNA?

A

produced a picture of the DNA molecule with X-ray crystallography. She found that a DNA has the shape of double helix (helical) Made of two strands
-the width of strands (help figure out that A goes with T and so on)

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9
Q

Who built the first model of DNA? What ideas from other scientists (name at least two) led them to be certain of which nitrogenous bases are bonded together.

A

Watson and Crick

-the width of bases and

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10
Q

What is the type of bond that holds the nitrogenous bases together? Why Is it important that this type of bonding mechanism is used in DNA?

A

Hydrogen bond

-They are weak so they break easily allowing for new dna to be build

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11
Q

What is meant by the “semiconservative model” of DNA replication?

A

Half new half old dna

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12
Q

What 3 things comprise a nucleotide? What molecules make up the backbone of DNA?

A

nitrogenous base,-phosphate group, and deoxyribose sugar,

-make up the backbone of dna-phosphate group, and deoxyribose sugar,

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13
Q

What is the difference between a purine and a pyrimidine?

A

Purine-too wide (2 carbon rings)

Pyramidene- too narrow (1 carbon ring)

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14
Q

What is the name of the site where DNA replication begins?

A

Origins of replication

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15
Q

Distinguish between origin(s) of replication in eukaryotes and prokaryotes.

A

In eukaryotes there are many but prokaryotes is only one

replication bubble for both

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16
Q

Which cell type replicates DNA faster, prokaryotes or eukaryotes?

A

Prokaryotes

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17
Q

What is the name of the Y-shaped region at the end of a replication bubble where new DNA strands are elongating?

A

Replication fork- parental strands of DNA are being unwound

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18
Q

Describe what “antiparallel” means in terms of DNA structure.

A
  • (their subunits run in opposite directions)
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19
Q

What direction does the DNA polymerase “read” the template strand?

A

3’-5’

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20
Q

What direction is the daughter strand synthesized? Why?

A

5’-3’

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21
Q

Differentiate between the leading strand and the lagging strand in DNA replication. What is an Okazaki fragment?

A
  • Leading- continuous elongation

- Lagging-elongation happens in segments (Okazaki fragments= segments where elongation occurs)

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22
Q

What is needed for DNA polymerase to bind to in order to begin replication? Why is it necessary?

A

An RNA primer

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23
Q

What enzyme untwists the double helix and separates the template DNA strands at the replication fork?

A

Helicase

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24
Q

What does the single-strand binding protein (SSBP) do during replication?

A

Keep strands separated

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25
Q

What is the function of topoisomerase?

A

-relieves the strain caused by tight twisting ahead of the replication fork by breaking, swiveling, and rejoining DNA strand

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26
Q

What enzyme synthesizes the RNA primers?

A

primase

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27
Q

What enzyme is responsible for continually synthesizing new DNA during elongation in both the lagging and leading strands?

A

-DNA polymerase 3

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28
Q

What enzyme is responsible for removing the RNA primers and replacing them with DNA?

A

-DNA polymerase I

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29
Q

If the DNA template strand reads TACGGCAGTCTGA, what would the DNA polymerase put on the daughter strand?

A

ATGCCGTCAGACT

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30
Q

Which enzyme joins the DNA fragments together?

A

Ligase

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31
Q

What is responsible for “proofreading” the DNA strands?

A

DNA polymerase

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32
Q

What is mismatch repair? What is nucleotide excision repair?

A

Mismatch repair= other enzymes correct errors in base pairing
-nucleotide excision repair= a nuclease cuts out and replaces damaged stretches of DNA

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33
Q

What is a thymine dimer? What environmental factor has been known to cause thymine dimers on DNA?

A

When two thymes pair together and there’s a kick

cause-UV rays

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34
Q

What are telomeres? Why are they important?

A

chromosomal DNA molecules have special nucleotide sequences at their ends

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35
Q

What is telomerase? What is its function?

A

catalyzes the lengthening of telomeres in germ cells- under study as a target for
cancer therapies
-Lengthens telomeres to maintain long chromosomes when creating an offspring

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36
Q

Differentiate between prokaryotic and eukaryotic DNA structure.

A

Prokaryotic DNA is organized into a single circular chromosome and eukaryotic DNA is organized into several linear chromosomes.

37
Q

Differentiate between location of prokaryotic and eukaryotic DNA.

A

Prokaryotic DNA can be found in the nucleoid region whereas eukaryotic DNA is found in the nucleus, enclosed by the nuclear membrane.

38
Q

Describe chromatin, and how it involves histones. What is a nucleosome?

A

Chromatin= a complex of DNA and protein bound to histones,
-histones=sections of protein -Proteins called histones are responsible for the first level of DNA packing in chromatin
A nucleosome consists of DNA wound twice around a protein core of eight histones, two of each of the main histone types

39
Q

Differentiate between euchromatin and heterochromatin

A
  • This condensed chromatin is called heterochromatin;

- the more dispersed, less compacted chromatin is called euchromatin

40
Q

What is “the direct manipulation of DNA for practical purposes”?

A

Genetic engineering

41
Q

What is a plasmid? Recombinant DNA?

A

-plasmids, small circular DNA molecules that replicate separately from the
bacterial chromosome
-The resulting plasmid is called recombinant DNA (plasmid with foreign dna)

42
Q

Explain the process of gene cloning using bacterial plasmids as vectors.

A

Gene of interest is inserted into a plasmid and as it replicates it creates more and more plasmid with the gen of interest

43
Q

What are restriction enzymes and why are they useful?

A

cut DNA molecules at specific DNA sequences- to obtain only the piece needed instead of the whole thing
- Scientist use them so they can cut DNA at specific locations

44
Q

What is gel electrophoresis and how is it useful?

A

To see the fragments produced by cutting DNA molecules with restriction enzymes, researchers use gel electrophoresis

45
Q

How can PCR yield many copies of a single target DNA sequence?

A

produces an exponentially growing population of identical DNA molecules- heating separates them and cooling joins them.

46
Q

Why is Taq polymerase used in PCR?

A

heat-stable DNA polymerase called Taq polymerase.

47
Q

What process cuts double-stranded DNA molecules as directed by a guide RNA that is complementary to the target gene?

A

Cas9- a nuclease that cuts double-stranded DNA molecules as directed by a guide RNA that is complementary to the target gene

48
Q

Where was the cas-9 system discovered? What is it used for?

A
  • discovered-in bacteria

- to cut viral DNA (viruses)

49
Q

What did Archibald Garrod suggest was the reasoning behind people with genetic disorders such as Alkoptonuria?

A

He thought symptoms of an inherited disease reflect an inability to synthesize a certain enzyme

50
Q

Explain the idea behind the one gene-one enzyme hypothesis. What did researchers later revise this hypothesis to?

A
  • each gene is responsible for producing one enzyme that affects a single step in the metabolic pathway
  • revised the one gene–one enzyme hypothesis to one gene–one polypeptide
51
Q

What is transcription? Translation? Where does transcription occur? Where does translation occur?

A
  • Transcription-the synthesis of RNA using information in DNA-produces messenger RNA (mRNA)-nucleus
  • Translation-the synthesis of a polypeptide, using information in the mRNA- ribosomes (RNA to protein)
52
Q

What is a codon? What is their function? Where are they found?

A
  • Three nucleotides paired together.
  • they form an amino acid
  • found in mRNA
53
Q

Why do codons have three bases and not two or one? How many total codons are there?

A

3^4 because 2^4 is only 16 and there are 20 amino bases

  • because they need to be transcribed into amino acids
  • 64 codons
54
Q

Explain the statement ‘the genetic code is redundant but not ambiguous.’

A

more than one codon may specify a particular amino acid but one codon can not specify more than one amino acid

55
Q

What enzyme is responsible for RNA synthesis during transcription?

A

RNA polymerase

56
Q

RNA synthesis follows the same base-pairing rules as DNA, with what exception?

A

Thymine becomes Uracil. Therefore the A base pairs with U instead of T.

57
Q

What is the name of the region where RNA polymerase attaches during transcription?

A

Promoter

58
Q

In Eukaryotes, what is added to the promoter region to turn the gene “on”?

A

Transcription factors

59
Q

Name the three stages of transcription.

A
  • Initiation
  • Elongation
  • termination
60
Q

The complete assembly of transcription factors and RNA polymerase II bound to a promoter is called ?

A

transcription initiation complex

61
Q

What box is crucial in forming the initiation complex in eukaryotes?

A

TATA box

62
Q

What is the primary transcript?

A

the initial RNA transcript from any gene prior to processing

63
Q

How are the “ends” of the mRNA modified after transcription? Do prokaryotes undergo RNA processing as well?

A

They get a tail and a cap.

Prokaryotes do not undergo RNA processing

64
Q

What are introns? Exons?

A

-The noncoding regions are called intervening sequences, or introns
The other regions are called exons and are usually translated into amino acid sequences

65
Q

What RNA splicing structure consists of a variety of proteins and several snRNPs?

A

Spliceosomes

66
Q

What is a ribozyme?

A

RNA molecules that function as enzymes

67
Q

What is alternative RNA splicing?

A

Many genes can give rise to two or more different polypeptides, depending on which segments are used as exons

68
Q

Because of RNA splicing, the number of different proteins an organism can produce is much greater than its number of ______.

A

Genes

69
Q

What two important structures are found at the ends of a tRNA molecule?

A
  • anticodon on one end \

- specific amino acid on the other end

70
Q

Why are molecules of tRNA not identical to each other?

A

Different anticodons recall for a different amino acid

71
Q

What term is used to describe flexible base pairing on a codon’s third base?

A

Wobble

72
Q

What is an anticodon? Why is it important?

A

base-pairs with an mRNA codon

73
Q

What is the function of the enzyme aminoacyl –tRNA synthetase?

A

To create accurate translation. It finds a correct match between a tRNA and an amino
acid,

74
Q

What two things is a ribosome composed of?

A

ribosomal proteins and ribosomal RNA(rRNA) (large and small subunit)

75
Q

Name and describe the three binding sites on a ribosome.

A
  • The P site holds the tRNA that carries the growing polypeptide chain
  • The A site holds the tRNA that carries the next amino acid to be added to the chain (arrival)
  • The E site is the exit site, where discharged tRNAs leave the ribosome (exit)
76
Q

What are the three stages of translation?

A
  • Initiation
  • Elongation
  • termination
77
Q

What three things must be present for initiation of translation?

A

-mRNA template, ribosomes, tRNAs, and start codon.

78
Q

During translation elongation, explain codon recognition, peptide bond formation, and translocation.

A

Cognon recognition= anticodon is going to recognize the codon
Peptide bond formation-amino acid from the tRNA is going to make a …
Translocation-codon moves to the next location (site)

79
Q

When will translation termination occur?

A

when a stop codon in the mRNA reaches the A site of the ribosome

80
Q

What does the release factor do to cause the release of the polypeptide?

A

-The release factor causes the addition of a water molecule instead of an amino acid. This reaction releases the polypeptide, and the translation assembly then comes apart
(hydrolysis)

81
Q

What is a polyribosome?

A

Strings of ribosomes

82
Q

What are the two kinds of ribosomes? What kind of proteins do they produce?

A
  • Free ribosomes-synthesize proteins that function in the cytosol
  • and bound ribosomes-make proteins of the endomembrane system and proteins that are secreted from the cell
83
Q

Where does protein synthesis (translation) always begin in the cell? What determines where translation finishes?

A

Begins in the cytoplasm

Translation finishes when there is a stop codon

84
Q

What is a mutation? A point mutation?

A
  • Mutations are changes in the genetic material of a cell or virus
  • Point mutations are chemical changes in just one nucleotide pair of a gene
85
Q

What has a greater affect on a protein, base-pair substitution mutations or frameshift mutations?

A

Frameshift mutations

86
Q

What two types of point mutations result in a frameshift mutation?

A

Deletion and insertion

87
Q

Differentiate between a silent mutation, missense and nonsense mutations.

A
  • Silent mutations have no effect on the amino acid produced by a codon because of redundancy in the genetic code
  • Missense mutations still code for an amino acid, but not the correct amino acid
  • Nonsense mutations change an amino acid codon into a stop codon, nearly always leading to a nonfunctional protein
88
Q

Physical or chemical agents that can cause mutations are known as

A

Mutagens

(radiation(sun)/ smoking

AP BIO (5 decks)

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