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Biology 1 > Exam 4 > Flashcards

Exam 4 Flashcards

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
Structure of DNA (compared to RNA)
``` Double-stranded Found in nucleus only Contains A,G,C, T Contains deoxyribose sugar Very large molecule ```
26
Classes of RNA
mRNA rRNA tRNA
27
Messenger RNA
Copies a genetic recipe from DNA in the nucleus and carries the recipe out into the cytoplasm
28
Ribosomal RNA
These are the ribosomes involved with protein synthesis | Serves as a workbench upon which the new protein molecules are put together
29
Transfer RNA
These RNA molecules pick up amino acids floating around in the cytoplasm and bring them to the site of protein synthesis
30
DNA to RNA to
Protein to trait
31
Transcription
Synthesis of mRNA using a DNA template | Occurs in the nucleus
32
Transcription steps
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
Translation
Production of a polypeptide from the genetic message carried by mRNA Occurs in the cytoplasm
34
Translation steps
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
Codon
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
Anticodon
A sequence of 3 nucleotide bases on tRNA that have the complimentary sequence of codons on mRNA
37
Triplet Code
Refers to the genetic code of mRNA codons that each consist of 3 nucleotide bases
38
The genetic code is
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
Redundancy is good because
It allows some mutations to slip through the cracks and the correct amino acid is specified anyway
40
The genetic code is a
Universal code | Most organisms use this code
41
Gene mutation
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
Frameshift mutation
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
Point mutation
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
Wobble Hypothesis
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
Mechanisms protecting against gene mutation
Semi conservative replication Base pairing rules DNA polymerase Having new mRNAs produced each time a protein product is needed
46
Mutagen
Any substance of agent that would cause a mutation or change in the DNA sequence Ex: radiation, chemicals in tobacco
47
Significance of mutations
Raw material for evolution (change) Most mutations are harmful Some are neutral A few may be helpful for survival
48
Gene
The unit of hereditary located on chromosomes
49
Gene expression
Occurs when the polypeptide product for which the given gene codes is produced
50
Controls over gene expression
``` Cell type Cell function Chemical conditions within cell Outside signals (hormones) ```
51
Lyonization
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
Four characteristics of cancer cells
Changes in plasma membrane and cytoplasm Grow and divide abnormally Weakened capacity for adhesion leading to metastasis Lethality
53
Oncogene
A cancer gene
54
Recombinant DNA technology and genetic engineering
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
Polymerase Chain Reaction (PCR)
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
RFLP
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
Plants genetic engineering
Frost resistance, pest resistance, plants that glow in the dark, etc
58
Animals genetic engineering
Production of transplantable organs, pigs that can produce human hemoglobin
59
Bacteria genetic engineering
Oil-eating bacteria, bacteria that can produce human insulin
60
Human genome project
Goal was to sequence all of the human chromosomes
61
Gene therapy
Goal is to replace a faulty gene with the proper gene

Biology 1 (5 decks)

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