DNA quiz Flashcards
1
Q
DNA
A
deoxyribosenucleicacid
- material that carries hereditary information
1
Q
protein synthesis turns (blank) into (blank)
A
sequence of bases, characteristics
2
Q
DNA is a polymer of
A
nucleotides
3
Q
per one nucleotide
A
- phosphate group
- deoxyribose sugar (5C)
- nitrogen-containing base
4
Q
what results in differentiation of DNA
A
- varying genes (that form all different proteins) and the varying sequence of nucleotides
5
Q
what is a gene?
A
contains the individual A,C,T,G parts of DNA
6
Q
Pyrimidines are…
A
- single ring
THYMINE
CYTOSINE
7
Q
purines are…
A
- double rings
ADENINE
GUANINE
8
Q
Watson and Crick
A
- DNA: double helix
- 2 strands
- Each strand has a sugar phosphate backbone on the outside
- bases on the inside: backbone=sugar+phosphate
9
Q
what causes a helix to have uniform width
A
- because a pyramiding pairs with a purine
10
Q
what does DNA need to be purified from
A
- other proteins
- cellular contaminants
11
Q
DNA Sample: 35% thymine
- what percent is guanine?
A
15%
12
Q
5’-ATTCCAG-3’
A
3’-TAAGGTC-5’
13
Q
DNA TO RNA
RNA TO DNA
RNA TO PROTIEN
A
- transcription
- reverse transcription
- translation
14
Q
what is DNA needed for
A
- growth
- repair
- reproduction: sexually/asexually
15
Q
what is the triplet code
A
- instructions for the 20 amino acids that DNA carries, occurs in chunks of three
- 3 BASES=1 AMINO ACID
16
Q
types of DNA replication
A
- conservative
- semi-conservative
- dispersive
17
Q
meselson-stahl experiment
A
- DNA replication is the focus
- bc of how strong DNA is, semi-conservative is inadmissible because of it needing to split
- grew cells in a nitrogen that made cells heavy
(isotope of N-to track new DNA and examines after each replication event) - used centrifugation: got heavier, moved to bottom
18
Q
DNA replication
A
1) initiation
- section of DNA is unwound to expose the bases for new base pairs
2) elongation
- 2 new DNA strands are created using the 2 ‘parental’ strands as templates
3) termination
- process completion and new DNA molecules reform into helixes
19
Q
5 key points of DNA
A
1) semi-conservative
2) anti-parallel
3) complementary
4) new DNA from 5 to 3
5) a fork is 1/2 a bubble
20
Q
initiation in depth
A
- DNA helixes breaks the H-bonds, forming the bubbles or FORKS
- single stranded binding potentials (SSBPs) attach to the free sections of the DNA to prevent it from bonding, and rewinding into a helix
21
Q
elongation in depth
A
- 2 new DNA strands are created using the two parental strands as templates
- DNA polymerase 3 adds new bases onto the parental strands by adding the 3’ end
- adds complementary to the parental strand
- must start at a RNA primer
laid by enzyme primase, bc DNA polymerase 3 has to latch on a primer before starting
22
Q
new bases can only be paired…
A
in the 5’-3’ direction
23
Q
leading strand
A
- strand that moves continuously towards the fork
1) primase attaches and adds RNA nucleotides to the parental strand
2) DNA poly 3 begins adding complementary nucleotides in the 5’-3’ direction
3) DNA polymerase 1 attaches to the primer+dismantles it
THIS REPLICATION PROCEEDS TOWARDS THE REPLICATION FORK
only putting 1 primer down–place to attach
- will always be new stuff for DNA polymerase to copy
24
Lagging strand
- one strand that moves AWAY from the fork
- moves slower causing the backtracking of DNA replication
1) primase attaches and adds RNA nucleotides to the parental strand
2) DNA polymerase 3 begins adding complementary nucleotides in 5'-3' (AWAY FROM THE FORK)
3) DNA polymerase 3 continues until it meets another RNA primer, then it detaches
4) Another DNA polymerase 3 attaches upstream of the go primer, repeating steps 2,3
**THIS CREATES SMALL DISCRETE PIECES OF DNA=OKAZAKI FRAGMENTS**
5) DNA ligase (glue-like) then joins the Okazaki fragments together by forming phospodiesteir bonds between nucleotides
25
Termination
1) DNA reforms its helical shape without enzymes
2) At the end of the lagging strands the Okazaki fragments and the parental strands won't match up perfectly because of RNA primer
** THIS ONLY HAPPENS IN EUKARYOTES, PROKARYOTES HAVE CIRCULAR CHROMOSOMES** -- no start/finish
3) Little bit of unpaired DNA will be snipped off, leaving the new strand slightly shorter than the original
26
as chromosomes replicate...
they get shorter, eventually will lose information and die
27
Proof Reading
**DNA poly 2 checks to make sure the H BONDS are present, if not, the enzyme removes the new nulceotides and inserts the proper one
- DNA polymerase 3
- mistakes happen 1/10 billion nucleotides
28
telomeres
- at the end of each chromosome is a telomere- a "nonsense" region of DNA (repeats of TTAGGG)
- these buffer the loss of DNA, when telomeres erode, the cell usually malfunctions and dies
- an enzyme known as telomerase replenishes telomeres, this enzyme is deactivated after a certain point
- it's reactivated in cancer cells making them immortal
29
DNA is coiled around
proteins=histones
30
what are telomeres
region at the ends of chromosomes used in cell division
- short arm: p
- long arm: q
31
genome
sum of all of an organisms DNA
- organized into packets=chromosomes
**Genomes can be organized into CODING and NON CODING regions
Coding: codes for proteins
Non-Coding: telomeres, centromeres
32
Non-coding proteins
- psuedogenomes: genes that are never expressed due to mutations
- GLO/GLUO in humans is an ex.
- a gene that is functional allows vitamin C synthesis from glucose, but a mutation that causes 1 enzyme in the process to go missing: we cant produce vitamin C naturally
33
another area of non-coding DNA=composed of transposons or transposable events
- little segments of DNA, more from 1 generation to another using our genomes
- not efficient function
- can insert themselves in a functional gene, causing a non-functional group (webbed fingers for ex.)
- Jumping genes that move around the genome that "copy, cut, and paste themselves" into chromosomes (ex. ALU)
34
ERV- endogenous retro virus
- extinct retroviruses (same class as HIV) that are stuck in our genome
- problems for human ancestors but have been knocked out by mutations in our DNA
- Account for 8% of human genome: in contrast, our genes only account for 2% of the 3 billion A,C,T,G
- they can be used to build phylogenic trees to test fossil records and restlessness
35
2% of our genome
coding region
36
CODING REGIONS
- gene: specific sequence of DNA that codes for proteins/RNA
- specific type, arrangement, number, and location cause variations btwn species
- NOT spread evenly among chromosomes
- No relationship btwn chromosomes size/number and the number of genes/organism "complexity"
37
SNPs
- single nucleotide polymorphism
- single base pair substitutions: cause SNPs
- SNPs can affect hair, drug reaction, or have no effects
38
MSTN gene
regulates insulin growth factor in muscles (IGF)
39
Gene structure
- each gene has regulatory elements that don't code for amino acids but enable the gene to be transcripts to MRNA (promoters and terminators)
- a common promoter (gene starts here)= TATA box
- always 2 promoters and 2 terminators needed to begin/end genes
EXONS: expressed into amino acid sequences
INTRONS: removed (deleted movie scene-intron analogy)
- ONLY MUTATIONS OF THE EXONS COUNT WILL SHOW ON AN ORGANISM
40
increased introns
increased stability, but increasing the efficiency and rate of mRNA translation
41
promoter
- start TATA
- cellular machinery gathers to build RNA message
- proteins bind to specific DNA sequences
42
Protein coding region
- nucleotides specify the order of the a.a. that make up a protein
43
intron
not expressed, cut out
44
exon
expressed
45
terminator
occur at the end of a gene and cause transmission to stop
- causes RNA polymerase to terminate transcription
