Chapter 8: The Molecular Basis of Inheritance Flashcards Preview

Barron's AP Biology > Chapter 8: The Molecular Basis of Inheritance > Flashcards

Flashcards in Chapter 8: The Molecular Basis of Inheritance Deck (64):
1

Griffith

Discovered that bacteria have the ability to turn harmless cells into virulent ones by transferring some of its genetic factors (bacterial transformation).

2

Avery, McLeod, McCarty

Proved that DNA was the genetic material, not proteins. Proved that the "transformation factor" from Griffith's work was DNA.

3

Hershey and Chase

Provided further evidence that DNA was the genetic material, not proteins.

4

Rosalind Franklin

Did DNA imagine through X-ray crystallography. Worked alongside Maurice Wilkins.

5

Watson and Crick

Identified the double helix shape of DNA. Depended on the use of Franklin and Chargaff's work.

6

Meselsohn and Stahl

DNA replication is semi-conservative.

7

Structure of DNA

DNA is a double helix, in which the two strands run in opposite directions (5' to 3', and 3' to 5'). Each nucleotide is made up of a nitrogenous base, a 5-Carbon sugar, and a phosphate group, where the nitrogenous bases are A, G, T, C. The nitrogenous bases are held together through hydrogen bonding.

8

Nitrogenous Base Pairing

A bonds with T
C bonds with G

9

RNA Structure

A single stranded helix consisting of four nucleotides: C, U, A, and G. The sugar in RNA is ribose.

10

Semiconservative Replication

When the DNA replicates, it uses one strand as a template for the new strand composed of complementary nucleotides. Thus, new DNA consists of one old strand and one new strand: semiconservative.

11

DNA Replication in Eukaryotes

1.

12

Avery, McLeod, McCarty

Proved that DNA was the genetic material, not proteins. Proved that the "transformation factor" from Griffith's work was DNA.

13

Hershey and Chase

Provided further evidence that DNA was the genetic material, not proteins.

14

Rosalind Franklin

Did DNA imagine through X-ray crystallography. Worked alongside Maurice Wilkins.

15

Watson and Crick

Identified the double helix shape of DNA. Depended on the use of Franklin and Chargaff's work.

16

Meselsohn and Stahl

DNA replication is semi-conservative.

17

Structure of DNA

DNA is a double helix, in which the two strands run in opposite directions (5' to 3', and 3' to 5'). Each nucleotide is made up of a nitrogenous base, a 5-Carbon sugar, and a phosphate group, where the nitrogenous bases are A, G, T, C. The nitrogenous bases are held together through hydrogen bonding.

18

Nitrogenous Base Pairing

A bonds with T
C bonds with G

19

RNA Structure

A single stranded helix consisting of four nucleotides: C, U, A, and G. The sugar in RNA is ribose.

20

Semiconservative Replication

When the DNA replicates, it uses one strand as a template for the new strand composed of complementary nucleotides. Thus, new DNA consists of one old strand and one new strand: semiconservative.

21

Process of DNA Replication in Eukaryotes

1. Replication begins at the origin of replication. Here, there are replication bubbles to separate the DNA, and replication forks where the DNA physically separates.
2. DNA polymerase elongates the DNA in the antiparallel direction.
3. DNA polymerase always builds DNA in the 5' to 3' direction, and adds nucleotides to the 3' end.
4. One strand, called the leading strand, is replicated linearly and in one string, while the lagging strand is replicated in short Okazaki fragments.
5. The DNA ligase seals up the Okazaki fragments.

Other proteins and enzymes that assist in DNA replication:
1. Helicases: Helps untwist the original strand of DNA at the replication fork.
2. Single-stranded binding proteins: Keeps the DNA from retesting back together during DNA replication.
3. Topoisomerase: takes away the tension the DNA goes through.
4. DNA nuclease: Gets rid of broken and bad pieces of DNA.
5. Telomeres: Repetitive strands of DNA added on by telomerase to keep from the erosion of DNA that occurs with ever replication of DNA.

22

Translating between DNA, mRNA, and tRNA

Going from DNA to mRNA, use GATC -> CUAG
Going from mRNA to tRNA, use the original DNA sequence, but replace all T's with U's.

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Steps from DNA to Protein

1. Transcription
2. RNA processing
3. Translation

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The three types of RNA in protein synthesis

1. mRNA: DNA is copied into mRNA in transcription, using CUAG.
2. rRNA: for structural purposes. Makes up the ribosome and the two ribosomal subunits.
3. rRNA: Carries the amino acid from the cytoplasmic pool to the mRNA at the ribosome. It has a binding site for the amino acid and the anticodon.

25

Transcription

Process from DNA to mRNA. It has 3 stages: initiation, elongation, and termination.

Initiation:
1. RNA binds to the promoter region.
2. The transcription factors recognize the TATA box.
3. The RNA polymerase binds to the promoter, and the next stage begins.

Elongation:
1. the RNA polymerase adds nucleotides to the 3' end.
2. Transcription unit: the length of DNA that gets turned into mRNA.

Termination: Elongation occurs for a little while longer after the RNA polymerase transcribes the termination sequence, which the mRNA is cut off from the DNA template.

26

RNA Processing

The step where the pre-mRNA is processed before it is sent out of the nucleus to the ribosome.

1. 5' cap is added to the 5' end.
2. Poly-A tail is added to the 3' end.
3. The introns are cut out using splicosomes and snRPS.

27

Alternative DNA Splicing

Different RNA molecules are produced from the same initial DNA transcript, depending on which pieces are treated as eons and introns.

28

Translation

Codons of the mRNA sequence is changed into the amino acid sequence. Also has three parts: initiation, elongation, and termination.

1. Initiation: When the mRNA attaches to the ribosomal subunit.
2. Elongation: Occurs when the tRNA brings the amino acid to the ribosome, and creates a polypeptide chain.
3. Termination: This continues until the ribosome reaches a stop codon. Then the release factor cuts off the polypeptide chain from the ribosome.

29

Wobble

The final base in the codon is not as important because it will probably create the same amino acid anyways.

30

Point Mutation

A mutation and change in just one base pair. Example: CAT -> FAT, where the C is exchanged for the F.

Sickle cell anemia is the result of a point mutation. Point mutations can sometimes give beneficial changes, or no change (due to wobble).

31

Insertion or Deletion

Also called a "frameshift," because the whole reading frame is shifted by one. Insertion occurs when an extra letter is inserted somewhere, and deletion occurs when one of the letters is lost.

32

Missense Mutation

When a normal codon becomes a stop codon, thus creating an early stop to the polypeptide sequence.

33

Viruses

Non living parasite that lives inside and controls the host cell. It is a puddle of DNA or RNA that lives inside a capsid or a viral envelope, and often can only infect one type of cell due to its characteristic specific membrane receptors.

34

Host Range

The range of organisms the virus can infect.

35

Bacteriophages

Most complex type of virus and can reproduce in two ways: lytic and lysogenic stage.

Lytic: The phage enters the cell and controls it, replicating many new bacteriophages. It then forces the cell to burst, which releases a whole new generation of phages at once.

Lysogenic: The phage enters the cell and becomes part of the DNA, called the "prophage." The prophage DNA then replicates as usual, creating new infected DNA. Soon, they transition to the lytic phase and burst.

36

Virulent Virus

The type of phage that only goes through the lytic stage.

37

Temperate Virus

The type of phage that undergoes lysogenic stage first, then the lytic stage.

38

Retrovirus

Contains RNA rather than DNA. The retrovirus replicates by entering the host cell and then using reverse transcriptase to use its own RNA as the new template for cDNA in the cell. This is strange because the usual progression of DNA replication goes from DNA to RNA.

Retrovirus then becomes a prophage, and the infected DNA is continually copied.

39

Transduction

Phage viruses can acquire pieces of bacterial DNA after infecting host after host. The transduction virus takes a piece of DNA from the host cell it infects, and inserts it into the next host cell.

40

Tryptophan Operon

A repressible operon, meaning that it is always on unless the repressor is activated.

Contains structural genes and a promoter. If the RNA polymerase attaches to the promoter, mRNA strand will be made. If trp is present, then it will act as a corepressor and activating the repressor, stopping the operon.

41

Lac Operon

Breaks down glucose and galactose. Repressor must not bind to the operator and RNA polymerase must bind to the promoter for the lac operon to operate.

Allolactose acts as the inducer that facilitate this process by binding to the active repressor, which stops the repressor, and allows RNA polymerase to bind to the promoter.

42

RNA Polymerase

Enzyme that transcribes RNA from the DNA template.

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Operator

The sequence of nucleotides near the start of an operon, and the binding of a repressor here stops the RNA polymerase from binding.

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Promoter

The binding site of the RNA polymerase.

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Repressor

Inhibits gene transcription, and binds to the operator.

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Regulator gene

Gene that codes for a repressor.

47

Prions

Misfolded proteins often found in the brain. Buildup can lead to fatal diseases, such as scrapie in sheep, mad cow disease, and Creutzfeldt-Jakob disease in humans.

48

Tandem repeats

Back-to-back repetitive sequences, and makes up telomeres.

49

Regulation at Chromatin Structure Level

Eukaryotic DNA is packed into histones. Changes in the histone structure and chromatin configuration (tighter or looser) will change the expression.

Acetylation will loosen chromatin structure and allow transcription.

50

Regulation by Methylation of DNA

Methylation of certain bases can silence the DNA. Also, addition of certain methyl groups can turn genes on.

51

Epigenetic Inheritance

The change in genome that are not permanent. Kind of like mutations, except do not last forever like mutations do.

52

Regulation by Transcription

RNA polymerase must bind to the promoter. The assistance of transcription factors can either enhance or inhibit transcription.

53

Regulation at Post-Transcriptional Level

Alternative RNA splicing: regulatory proteins can decide which parts of the RNA are treated as introns and exons, which plays a major role in deciding what parts of the gene are expressed.

54

Degradation of mRNA

Bacteria mRNA degrades incredibly quickly, which might explain why bacteria change their patterns of protein synthesis so quickly.

In contrast, human mRNA must translate some things for weeks on end, in which the mRNA does not change or re-express quickly.

55

miRNA

microRNA. Targets specific mRNAs to either degrade or block them.

56

siRNA

Similar to miRNA in size and function.

57

piRNA

Guide PIWI proteins to complementary RNAs

58

Proteins that are Modified Post-Translational Level

This is the final chance to alter gene expression. After the protein emerges from the ribosome, some can immediately start "working," and others must be activated first.

59

Recombinant DNA

Taking DNA from two or more sources and combining them into one DNA molecule. The branch of science that uses this practically is biotechnology or genetic engineering.

60

Restriction Enzymes (Tools of Biotech)

Restriction enzymes cut DNA at specific sequences of sites, which leaves sticky ends that can join to other sticky ends temporarily. These create restriction fragments.

61

Gel Electrophoresis

Separates large molecules of DNA by their rate of movement. Often used to separate proteins and amino acids, which must first be cut by restriction enzymes to migrate through the gel.

62

DNA Probe

Radioactively labeled single strand of nucleic acid molecules used to tag a specific sequence in DNA. It naturally binds to its complementary sequence.

63

Polymerase Chain Reaction (PCR)

Can copy or amplify a piece of DNA very quickly. However it has some limitations: contamination, some info about the DNA must already be known, and the sequence must be very short.

64

RFLPs

A restriction fragment is the DNA that is left after it is treated with restriction enzymes. However, people have realized that the restriction fragment pattern is unique to every individual, like fingerprints. RFLPs can be used to identify perpetrators in paternity suits, rape, and murder cases.