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81 Cards in this Set

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What does DNA stand for?
Deoxyribonucleic acid
Can other moleculds replicate and repair themselves like DNA?
No
What is the Theory of Engulfment?
Mitochondria and chloroplasts were seperate organisms (because each have a small amount of DNA), that were engulfed by unicellular organisms. The theory of engulfment describes how these organelles came to be part of the commen eukaryotic cell (chloroplast only for plants).
What are chromosomes made of?
DNA and protein
How many base pairs are there in the human genome?
3 billion
What does DNA ensure?
The continuity of life (chimps bear chimps, not elm trees).
What is the blueprint for proteins?
DNA
What was thought to be the heriditary material prior to the 1940s? Why?
Proteins, because they are composed of 20 possible amino acids (many more combinations than the 4 nucleotide base pairs of DNA).
Who discovered the double helix structure of DNA?
Watson and Crick 1953, Nobel prize 1962.
What is the base unit of DNA?
Nucleotides
What composes a nucleotide?
Phosphate, Sugar (5-carbon deoxyribose), a nitrogen base pair.
What are the nitrogen base pairings in DNA?
Adenine -> Thymine
Cytosine -> Guanine
Why are the nitrogen base pairs A and T, and C and G?
A purine (2 rings) must pair with a pyrimidine (1 ring), so that the width of the DNA remains constant.

Also the hydrogen bonding that forms between the base pairs is much stronger this way.
How many H-bonds between A and T? between C and G?
A and T = 2 H-bonds
C and G = 3 H-bonds
When is DNA replicated?
During S phase of interphase
Why is DNA replication called semiconservative?
Because each parent strand becomes half of the new DNA molecule. New DNA molecules are identical to parent DNA (the parent is the template or mold for the new DNA).
What is the first step to DNA replication?
DNA twists and unzips.
What do DNA polymerases do?
They are enzymes that join the new nucleotides to the parent strands.
What direction do DNA polymerases join the new nucleotides to the parent strand?
A 5'3' direction (resulting in a leading and lagging strand).
Which is formed continuously, the leading or lagging strand?
The leading strand.
What is a mutation?
An error in the sequence of nitrogen base pairs of DNA. It is not a chromosomal abnormality.
Are mutations inheritable?
Yes
What is the frequency of a DNA mutation?
1/billion
Are mutations more likely to be lethal in somatic or gametic cells?
Gametic.
What percent of DNA do humans use?
3%
What are DNA primers?
A specific sequence of nucleotides that DNA polymerase looks for to start replication.
What increases the chance of a mutation?
Certain chemicals, radiation (carcinogens, mutagens)
What is the function of DNA ligase?
It fuses the parent and daughter strands of DNA together.
What are endonucleases?
They are enzymes present in all cells, they cut strands of DNA.
What are restriction enzymes?
Endonucleases in bacteria, cut foreign DNA. There are over 200 kinds. Essentially biological scissors
Why is DNA replication called semiconservative?
Because each parent strand becomes half of the new DNA molecule. New DNA molecules are identical to parent DNA (the parent is the template or mold for the new DNA).
What is the first step to DNA replication?
DNA twists and unzips.
What do DNA polymerases do?
They are enzymes that join the new nucleotides to the parent strands.
What direction do DNA polymerases join the new nucleotides to the parent strand?
A 5'3' direction (resulting in a leading and lagging strand).
Which is formed continuously, the leading or lagging strand?
The leading strand.
What is a mutation?
An error in the sequence of nitrogen base pairs of DNA. It is not a chromosomal abnormality.
Are mutations inheritable?
Yes
What is the frequency of a DNA mutation?
1/billion
Are mutations more likely to be lethal in somatic or gametic cells?
Gametic.
What percent of DNA do humans use?
3%
What are DNA primers?
A specific sequence of nucleotides that DNA polymerase looks for to start replication.
What increases the chance of a mutation?
Certain chemicals, radiation (carcinogens, mutagens)
What is the function of DNA ligase?
It is the DNA glue and repair system. (Fuses parent strand to daughter strand in DNA replication).
What are endonucleases?
They are enzymes present in all cells, they cut strands of DNA.
What are restriction enzymes?
Endonucleases in bacteria, cut foreign DNA. There are over 200 kinds. Essentially biological scissors
What is biotechnology?
The use of living things (usually bacteria) to create products.
Ex. nutrasweet, glue
What is a transgenic organism? What are the advantages? Describe the process.
An organism containing foreign DNA.

Organisms such as bacterium can make proteins from a therapeutic gene from a donor faster. They then duplicate the donor gene along with its own, and pass it on to other bacteria during conjugation (exchanging plasmids).
What is gene therapy?
Inserting genes into human cells (such as insulin).
What is an oncogene?
A cancer causing gene.
Where does protein synthesis occur?
In the ribosomes found only in the cytoplasm/
What are the nucleotides of RNA?
U and A
C and G
ribose instead of deoxyribose
How many strands are in RNA?
1
What is the function of mRNA?
Transferring message from the nucleus to the cytoplasm to facilitate the formation of specifiec proteins.
What are the 3 types of RNA?
mRNA (messenger)
rRNA (ribosomal)
tRNA (transfer)
What is the function of proteins?
They compose cells, organelles, muscle, hair, hormones, antibodies, EMZYMES!!!
What are enzymes?
catalysts (speed up reactions) - lower activation energy.
What is the primary structure of proteins?
An amino acid sequence (20 possible amino acids). A long chain.
What is the secondary structure of proteins?
Twisting like a rope
What is a tertiary structure of proteins?
Globular structure where amino acid chain that has twisted like a rope folds into a 3d shape.
What controls the sequence of AA in a protein?
The sequence of nucleotides in DNA.
What is the structure of an amino acid?
The acid group and the amino group (N group!!!!!). There is then the R group that is different from each amino acid.
What is RNA transcription?
The process by which DNA code is transferred into RNA. A portion of DNA where specific protein gene is located uncoils and unzips. The RNA polymerase enzyme attaches to DNA initiator sequence.
How many DNA strands do RNA nucleotides join to?
Only one, because RNA is single stranded.
What is an RNA mutation?
Changes in sequence of RNA, causing the protein produced not to function at all or differently (sometimes has no effect).
DNA -> DNA
replication
DNA -> mRNA
transcription
mRNA -> Protein
Translation
When does transcription stop?
When mRNA reaches the termination codon.
What are functions of mRNA other than sequencing for protein?
When to translate RNA into protein, how long (how many copies)
What are RNA retroviruses?
Viruses that reverse the process of normal transcription by using reverse transcriptase. mRNA trascripts to DNA!
How can 4 nucleotides code for 20 different AA?
4 base pairs in combos of 3 yeild 64 combos (4 to the power of 3). some redundancy because there is only 20 AAs.
What is a CODON?
A triplet of nucleotides. Codons initiate and terminate protein synthesis.
What is the process of translation?
-mRNA attaches to ribosome
-initiator codon turns on protein synthesis
tRNA transfers an AA from cytoplasm to a mRNA-ribosome complex. The tRNA has the corresponding anticodon to the mRNA codon and carries a specific AA for that codon / anticodon.
-tRNA moves to cytoplasm to find another AA.
-AA on ribosome-mRNA complex joins to form a peptide chain through the process of dehydration synthesis.
-terminator codon ends protien synthesis.
What is a polysome?
Several ribosomes translating simultaneously.
What do mutagenic agents do?
Change the sequence of nucleotides in DNA -> new mRNA -> new AA -> new protien.
What are structural genes?
Codes for the building of a protein, ex. insulin
What is a regulator gene?
It turns on / off a segment of DNA by producing a regulator protein that represses production of structural gene.
What is cancer?
Uncontrolled cell growth. Can be caused when a mutagen causes the oncogone to be transposed (moved to another site) away from its regulator gene so it will be free to turn on cell division indefinately.
Do most normal cells contain oncogenes? Why do these cells function normally?
Yes, but they function normally because they are regulated.
What is the ames test 1?
Salmonella bacteria that are mutated so they cannot produce histidine (therefore cannot grow) ---> add test chemical ---> If they grow we know the microbe must have mutated, the more bacterial growth the more mutagenic the chemical is.
What is ames test 2?
Add chemical to liver enzymes for digestion ---> Add to salmonella bacteria that are mutated so they cannot produce histidine ---> If bacteria grow, we know the microbe must have mutated. The more bacterial growth the more mutagenic the chemical is.