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Biology 1 > Exam 4 > Flashcards

Exam 4 Flashcards

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1
Q

Hershey Chase Experiment

A

They used bacteriophages (viruses that infect bacteria)

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2
Q

Protein contains

A

Sulfur

NOT phosphorus

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3
Q

DNA contains

A

Phosphorus

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4
Q

Adenine and Guanine

A

Double ringed purines

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5
Q

Thymine and Cytosine

A

Single-ringed pyramidines

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6
Q

A purine always pairs with

A

A pyrimidine

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7
Q

Griffith’s Transformation

A

Used pneumonia bacteria that infected mice
Type R bacteria are non virulent (not deadly)
Type S bacteria are virulent (deadly)—they produce a slime coat that the immune system has difficulty fighting

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8
Q

Bacteriophages can replicate in an environment with

A

Radioactively tagged sulfur

This was incorporated into their protein coats

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9
Q

Infected bacteria with sulfur were

A

NOT radioactive, so that means the protein costs of the bacteriophages (viruses) did not enter the bacteria

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10
Q

Bacteriophages were also allowed to replicate in an environment with

A

Radioactively tagged phosphorus

This was incorporated into their DNA

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11
Q

Infected bacteria with phosphors were

A

Radioactive, so that must mean the DNA of the bacteriophages (viruses) did enter the bacteria

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12
Q

Point of Griffith’s experiment:

A

DNA is the genetic material

NOT protein

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13
Q

Nitrogenous bases

A

Adenine
Guanine
Thymine
Cytosine

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14
Q

DNA is located in

A

The nucleus of eukaryotic cells

Nucleoid region of prokaryotic cells

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15
Q

Sugar phosphate backbone consists of

A

Alternating deoxyribose sugar units and phosphate groups

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16
Q

Semi conservative replication

A

How DNA replicates itself
Old strands are used as the template pattern for making the new strands
In a duplicated chromosome, there exists one old strand and one new strand of DNA

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17
Q

Steps of semi conservative replication

A

Hydrogen bonds joking the two strands of DNA together break, allowing DNA to unwind
Complementary nucleotides pair up with those on the old strands of DNA in order to make new strands
Two daughter DNA molecules form that are identical copies of each other

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18
Q

Accuracy of DNA replication

A

A mismatched nucleotide occurs about once per 100,000 base pairs

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19
Q

DNA polymerase

A

Proofreads the DNA strand checking for mismatched pairs
Most, but not all, mismatches are repaired. After “proofreading,” the error rate is only about one per 10 billion base pairs

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20
Q

DNA ligase

A

Seals the crack left in the sugar-phosphate backbone after the mismatched base(s) are excised and replaces with the correct bases

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21
Q

Histones

A

Little protein spoils that help organize the DNA

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22
Q

Nucleosomes

A

Histone proteins with two wraps of DNA on them. These are important in organizing DNA because this is how the DNA strand is condensed

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23
Q

One gene one polypeptide hypothesis (one gene one enzyme hypothesis)

A

One gene codes for the production of one specific polypeptide (protein, enzyme, hormone)

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24
Q

Structure of RNA

A 
Single stranded
Found in nucleus and cytoplasm
Contains A,G,C, Uracil
U instead of T!!!
Contains ribose sugar
Relatively small molecule
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25
Q

Structure of DNA (compared to RNA)

A 
Double-stranded
Found in nucleus only
Contains A,G,C, T
Contains deoxyribose sugar
Very large molecule
26
Q

Classes of RNA

A

mRNA
rRNA
tRNA

27
Q

Messenger RNA

A

Copies a genetic recipe from DNA in the nucleus and carries the recipe out into the cytoplasm

28
Q

Ribosomal RNA

A

These are the ribosomes involved with protein synthesis

Serves as a workbench upon which the new protein molecules are put together

29
Q

Transfer RNA

A

These RNA molecules pick up amino acids floating around in the cytoplasm and bring them to the site of protein synthesis

30
Q

DNA to RNA to

A

Protein to trait

31
Q

Transcription

A

Synthesis of mRNA using a DNA template

Occurs in the nucleus

32
Q

Transcription steps

A
  1. Chemical message sent to the chromosome with the gene that produces a certain polypeptide
  2. DNA unzips to expose the gene
  3. mRNA is built as complementary nucleotides pair up with the bases on the DNA strand
  4. Once mRNA is built, it leaves the gene and moves out into the cytoplasm; DNA zips up again
33
Q

Translation

A

Production of a polypeptide from the genetic message carried by mRNA
Occurs in the cytoplasm

34
Q

Translation steps

A
  1. mRNA associates with ribosomes in the cytoplasm
  2. The genetic message is read 3 bases at a time (3 bases = 1 codon)
  3. tRNA brings an amino acid to the mRNA rRNA complex; the anticodon on tRNA pairs up with the codon on mRNA
  4. second tRNA brings an amino acid and holds it in place until a peptide bond forms between the two amino acids
  5. first tRNA leaves the complex, the rRNA (ribosome) moves down the mRNA by one codon, and the process continues until the polypeptide is complete
35
Q

Codon

A

A sequence of 3 nucleotide bases on mRNA that codes for a single amino acid (or a stop signal)
61 specify amino acids and 3 specify STOP

36
Q

Anticodon

A

A sequence of 3 nucleotide bases on tRNA that have the complimentary sequence of codons on mRNA

37
Q

Triplet Code

A

Refers to the genetic code of mRNA codons that each consist of 3 nucleotide bases

38
Q

The genetic code is

A

Degenerate or redundant
This means that some amino acids are specified by more than one codon, BUT each codon only specifies one amino acid (or stop signal)

39
Q

Redundancy is good because

A

It allows some mutations to slip through the cracks and the correct amino acid is specified anyway

40
Q

The genetic code is a

A

Universal code

Most organisms use this code

41
Q

Gene mutation

A

A change in the DNA sequence of a gene

Can be passed on to the next generation only if they occur in sex cells

42
Q

Frameshift mutation

A

Involves an addition or deletion of one or more nucleotide bases
Result is a shift in the reading frame of mRNA
The consequences are not as bad if the addition or deletion is a multiple of 3
If the mutation exists in DNA, mRNA will copy the error each time
Sometimes mRNA will copy incorrectly even if DNA is correct
CHANGES # OF BASES

43
Q

Point mutation

A

The substitution of one nucleotide base for another
Result is the incorrect amino acid may be inserted into the protein chain
Depends on where the point mutation occurs
DOESNT CHANGE # OF BASE

44
Q

Wobble Hypothesis

A

For many codons, the third base may “wobble” or vary and still code for the same amino acid
A certain level of mutation can be tolerated

45
Q

Mechanisms protecting against gene mutation

A

Semi conservative replication
Base pairing rules
DNA polymerase
Having new mRNAs produced each time a protein product is needed

46
Q

Mutagen

A

Any substance of agent that would cause a mutation or change in the DNA sequence
Ex: radiation, chemicals in tobacco

47
Q

Significance of mutations

A

Raw material for evolution (change)
Most mutations are harmful
Some are neutral
A few may be helpful for survival

48
Q

Gene

A

The unit of hereditary located on chromosomes

49
Q

Gene expression

A

Occurs when the polypeptide product for which the given gene codes is produced

50
Q

Controls over gene expression

A 
Cell type
Cell function
Chemical conditions within cell
Outside signals (hormones)
51
Q

Lyonization

A

The phenomenon in female mammals where one of the two X chromosomes is inactivated. The inactivated X becomes a Barr body. The same X will be inactivated in all cells from that particular cell line
Female mammals that are heterozygous for alleles on the X chromosomes are mosaic or “patchwork” for the traits, with some cells expressing the dominant trait and other cells expressing the recessive trait

52
Q

Four characteristics of cancer cells

A

Changes in plasma membrane and cytoplasm
Grow and divide abnormally
Weakened capacity for adhesion leading to metastasis
Lethality

53
Q

Oncogene

A

A cancer gene

54
Q

Recombinant DNA technology and genetic engineering

A

Both involve the manipulation and transfer of genes from one organism to another or the production of a DNA molecule by combining DNA from different sources

55
Q

Polymerase Chain Reaction (PCR)

A

A fast and efficient way to amplify DNA from a small sample obtained from a crime scene or fragment of an organism
Cycles of heating and cooling are used to cause DNA to unwind, replicate, and reform helices over and over again
PCR is very important, especially if only a very small quantity of DNA is recovered. Many copies can be made for experimentation, finger-printing

56
Q

RFLP

A

Restriction Fragment Length Polymorphism
These are fragments or segments of DNA obtained by using restriction enzymes to cut DNA in precise places. These fragments are then used to make a DNA fingerprint for identification purposes

57
Q

Plants genetic engineering

A

Frost resistance, pest resistance, plants that glow in the dark, etc

58
Q

Animals genetic engineering

A

Production of transplantable organs, pigs that can produce human hemoglobin

59
Q

Bacteria genetic engineering

A

Oil-eating bacteria, bacteria that can produce human insulin

60
Q

Human genome project

A

Goal was to sequence all of the human chromosomes

61
Q

Gene therapy

A

Goal is to replace a faulty gene with the proper gene

Biology 1 (5 decks)

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