Test 3

Question 1

DNA structure

Answer 1

-Nucleotide pairs are bound together by hydrogen bonds.
-Sugar in DNA is Deoxyribose
-Nitrogenous based (ACTG)
-More hydrogen bonds in G,C than T,A so harder to pull
-The origin of DNA replication contains lots of A + T.
-The strands are antiparallel. (Sugars are pointed in opposite direction) 5’ (prime) end and 3’ end.
-DNA are instructions for making proteins
-Gene, instructions for a particular protein (amylase)

Question 2

Seperates the two strands of DNA?

Answer 2

Helicase

Question 3

Creates a complementary strand of DNA?

Answer 3

DNA polymerase
-reads from 3’ to 5”
-creates from 5’ to 3’
Primase adds a primer (piece of RNA), since it can only add nucleotides to existing strand.

Question 4

Leading strand? Lagging strand?

Answer 4

-DNA polymerase follows helicase getting long new strand of DNA.
-Lagging——- where DNA polymerase move away from helicase. This is where pieces of fragments are made (Okazaki fragments).

Question 5

Lagging strand? Enzymes………. RNASE H? LIGASE?

Answer 5

-Lagging——- where DNA polymerase move away from helicase. This is where pieces of fragments are made (Okazaki fragments).
—-WHEN REPLICATION COMPLETED—-
–RNASE H … removes primers and get replaced by DNA
–Ligase.. joins the fragments

Question 6

Semiconservative

Answer 6

Each strand contains one old and one new strand
- Eukaryotes these are sister chromatids seperated by Anaphase 1 (mitosis) and Anaphase II (meiosis)
- Prokaryotes , separated by Binary Fission.

Question 7

DNA replication Thermodynamically unfavorable (creating larger molecules)

Answer 7

-made to occur by coupling it by phosphate removal.
-each nucleotide is brought in as tri-phosphate so 2 phosphates are removed to link together.

Question 8

PCR (polymerase chain reaction) check list

Answer 8

-Thermocycle (applies heat to denature DNA, breaks hydrogen bonds)
-Starting DNA
-Primers specific to DNA
-DNA polymerase (from thermophile)
-Nucleotides (triphosphates)

1. This is useful for
   – genetic engineering
   –DNA fingerprinting
   –DNA sequencing

Question 9

DNA sequencing

Answer 9

-Determines the sequence of nucleotides.
-Identifies microorganisms
-uses a mix of dideoxy + regular DNA nucleotides
-Starts with a primer then it either adds a regular nucleotide or dideoxynucleotide in which it would stop.
-it ends up with fragments of different length with fluorescent end.
-DNA is negatively charged-pulled towards + electrode
-Smaller fragments travel faster
- Fragments get read by fluorescent detector.

Question 10

Dideoxynucleotide

Answer 10

-No hydroxyl group -OH in carbon 2 and 3
-No -OH in carbon 3, no new nucleotides added.
-Fluorescent components are added to identify them

Question 11

Proteins are made?

Answer 11

On ribosomes

Question 12

Transcription

Answer 12

-Makes a temporary RNA copy of a gene
-Only one strand gets copied, the coding strand
-Promoter makes the start of a gene, and the end of the gene is called the termination sequence.
-RNA polymerase reads 3’ to 5’ makes a complimentary RNA copy (messenger RNA)
-Prokaryotes, messenger RNA immediately ready for translation
-Eukaryotes, RNA need to be processed, INTRONS (extra letters of DNA not necessary for making protein)

Question 13

Translation

Answer 13

-Reading instructions to make protein.
-mRNA (messenger RNA) bind with ribosome
-2 tRNA (transfer RNA) molecules bring in the first amino acids
-Ribosome catalyzes dehydration transferring amino acid from 1st tRNA to second tRNA.
- Ribosome moves down one codon -empty tRNA falls off, next tRNA brings in next amino acid.
-Ribosome catalyzes dehydration synthesisk repeating step 3 and 4 until it reaches a stop codon (UAG)

—————mRNA can be reused, ribosome units find another mRNA to translate, tRNA needs another amino acid.
– In prokaryotes translation can start before transcription is finished.

Question 14

Codon chart

Answer 14

-Each codon codes for a particular amino acid
-It is for messenger RNA and not for the anticodon

Question 15

Mutation

Answer 15

change in DNA due to
—-DNA polymerase errors
—-DNA demage

Question 16

1.Silent mutations
1.missense mutations
2.nonsense mutations
3.frameshift mutation

Answer 16

1. when DNA changes but polypeptide doesn’t
2. change in amino acid
3. stop codon forms
4. addition or deletion of bases.

Question 17

Ames test

Answer 17

Whether a compound causes mutations (mutagens).
-Mutations are often carcinogens in humans.
Add chemical to be tested + liver enzymes (liver breaks down chemical and sometimes into worse products) this allows all chemical components.

Question 18

carcinogen

Answer 18

substance capable of causing cancer.

Question 19

Gene regulation

Answer 19

Process of controlling which genes are being transcribed (on)

Question 20

Constitutive Genes

Answer 20

not regulated, expressed constantly (ex, glycolysis enzymes)

Question 21

Inducible genes

Answer 21

Usually off but can be turned on (ex for catabolism)
the repressor protein is active

Question 22

Operon (in prokaryotes)

Answer 22

All genes regulated/transcribed together

Question 23

gene regulation when ex (lactose present)

Answer 23

lactose binds to represent. letting RNA polymerase bind to promoter so that transcription can occur.

Question 24

cAMP

Answer 24

-starvation signal
- binds to cAMP receptor protein
-which they both bind to promoter acting as transcription factor (increases transcription). it encourages RNA polymerase to bind so more genes for certain molecules can be made more.

Question 25

Repressible genes

Answer 25

usually on, can be turned off (Most genes for anabolism)
Repressor is inactive.
When there is enough of that certain molecule, that certain molecule binds to repressor activating it so that RNA polymerase can’t bind to promoter.

Question 26

In Eukaryotes there is no operons

Answer 26

All genes have their own promoter.
–if there is an enhancer away from the promoter, transcription factors bind to the enhancer which encourages RNA polymerase to bind to the promoter.