Exam 2 Flashcards
(T/F) DNA, RNA, and Protein are different from species to species unlike carbs and lipids which are universal.
True
What were the 3 laws of inheritance Mendel published?
- Proposed traits were not blended but given through sets of pairs (alleles: Aa, aa, AA)
- Proposed mother and father each contributed a pair
- Presented inheritance in punnett square
What is the structure of DNA?
-A 5 carbon sugar backbone with a phosphate group on the top and a nitrogenous base attached on the side.
What are the 4 nitrogenous bases of DNA?
- A (Adenine)
- G (Guanine)
- C (Cytosine)
- T (Thymine)
How do the 4 nitrogenous bases pair up in DNA?
What does this mean?
A to T
G to C
Means that they will always be present in equal amounts
Which 2 nitrogenous bases are the purines?
A and G
Which 2 nitrogenous bases are the pyrimidines?
T and C
What is a bacteriophage?
A virus that has a body made of protein and has DNA within it.
How is DNA structure shaped?
Double Helix
How does DNA form?
- Nucleotides chain together and twist into double helix
- Nitrogenous bases bond together in middle
DNA must be anti-parallel meaning:
One nucleotide strand is oriented in the 5’ to 3’ direction while the other is in the 3’ to 5’ direction.
The 5’ end of DNA is a _______
5-carbon phosphate group
The 3’ end of DNA is a _______
3-Carbon hydroxyl group
How do nucleotides bond together to form DNA strand?
5-carbon phosphate attacks a 3-carbon hydroxyl and bonds to form a chain
What is a nucleoside?
A sugar + a phosphate group
What is a nucleotide?
A nucleoside + a nitrogenous base group
What type of bond connects nucleotides?
phosphodiester bond
How many hydrogen bonds are present when A and T bond?
2
How many hydrogen bonds are present when G and C bond?
3
Humans have ______ billion base pairs of DNA.
3.3
Human DNA laid end to end would be ____ft long which is _________ times larger than the nucleus of a cell.
6
260000
If a nucleus was 1 inch long, DNA to fit in it would be ____ miles long.
4.1
Because so much DNA must fit into a nucleus, how do organisms fix this problem?
-By wrapping DNA around proteins called Histones
Do histones exist in prokaryotes?
No
What are the 5 types of histones?
Which of these is special?
- H1
- H2A
- H2B
- H3
- H4
Special: H1
When a double-helix of DNA is wrapped around a histone ball, this is called a__________.
Nucleosome
What is the special role of the H1 Histone?
It attaches to the side of a nucleosome (Wrapped DNA helix and another histone) and continues to roll them into a larger ball.
After the H1 histone has dones its job, what is the final product called?
A solenoid
DNA is a _____ ___________ molecule.
self-replicating
(T/F) DNA is the same in every cell within an organism.
True
What were the 3 hypothesized methods of DNA replication?
- Conservative
- Semi-conservative
- Dispersive
What is the principle of conservative replication?
The parent DNA helix synthesizes a copy of itself and the result is one DNA helix that uses the same 2 strands as the parent and one new DNA helix that have 2 identically copied strands from the parent
What is the principle of semi-conservative replication?
The 2 parent strands of DNA separate and each acts as a template for synthesis of a new complimentary strand. The result is 2 DNA helixes with one parent strand and one daughter strand.
What is the principle of dispersive replication?
Parent strands are mixed with daughter strands to form 2 new mixed strands of DNA.
What is the parent/old strand of DNA referred to as in replication?
Template strand
Does the parental DNA remain intact during replication?
Yes
Which form of replication was proven to be the correct one?
Semi-conservative
DNA replication is an ________ (endergonic/exergonic) reaction.
endergonic
Does a cell use ATP to power process of DNA replication?
NO!
What is used to power the process of DNA replication?
dNTP
What enzyme enables DNA replication?
DNA polymerase
Where is a DNA helix split during replication?
At the origin of replication (OR)
What enzyme breaks the Hydrogen bonds during DNA replication? What does it burn to do this?
Helicase
ATP
What enzyme lays the primer stretch on top of one strand for DNA polymerase to hold onto?
Primase
During replication, what is the strand that DNA polymerase continues on til the end without fragmenting?
Leading strand
During replication, one strand is continually fragmented as DNA polymerase continues to bump into new sections of primase track. What strand is this?
Lagging strand
What are the fragments on the lagging strand called?
Okazaki fragments
Is primer tracks of primase left or removed after DNA polymerase has got started replicating template strand?
It must be removed
What enzyme seals the gap left between DNA fragments after primase tracks are removed?
Ligase
What direction does DNA replication happen in in reference to the DNA double helix?
Both but on opposite strands. Once the parent strands are split, and the primer tracks are laid, DNA polymerase takes off down each parent strand in BOTH directions from the origin of replication. Replication always occurs in the 5 to 3 direction. This means that for leading strands, replication is done from the origin of replication outward and for lagging strands, replication is done toward the origin of replication.
In what what is DNA ALWAYS replicated?
5’ to 3’ direction
What were the 3 methods of repair that DNA Polymerase has of checking and repairing errors?
- Proofreading Repair
- Mismatch Repair
- Excision Repair
What happens if the wrong base pair is copied during DNA replication?
If a wrong pair was copied, the DNA will bulge due to repulsive forces between incorrect base pairs.
What happens during proofreading repair?
DNA polymerase will detect the buldge caused by repulsing incorrect base pairs. It will then backup and replace the incorrect letter before continuing replication.
A small area at the end of a DNA strand cannot be copied, this causes ______ in organisms.
aging
What do some cells do with the bit that gets cut off?
Fills the gap with Telemerase and small bit of RNA template.
What are the ends of chromosomes known as?
Telomeres
What is the coding in a telomere?
non-sense just to fill space.
Humans only create telomeres at the end of _____, ______, and ______ cells.
Sperm, egg, and stem
This is used to sequence DNA in a lab
Dideoxynucleotide sequencing
You ______ (can/cannot) use dideoxynucleotides to build DNA.
CANNOT
How does Dideoxynucleotide sequencing work?
These were mixed with other nucleotides that were labelled with different colors for each of the 4 base pairs. This let him see how they were aligned shortest to longest which gave him the sequence of the DNA.
What is the order that central dogma goes in?
1) DNA Replication
2) RNA Transcription
3) Protein Translation
What 2 principles did “central dogma of molecular bio. suggest?
- DNA is a self-replicating molecule
- That it is a strand of information
Genes encode for specific ________ that are needed to create/intake/synthesize other ________. This creates the __________ pathway of life.
- enzymes
- enzymes
- biochemical
DNA (can/cannot) become RNA DNA (can/cannot) become protein RNA (can/cannot) become protein RNA (can/cannot) sometimes become DNA Protein (can/cannot) become RNA or DNA
- can
- can
- can
- can
- cannot
What are 4 differences between RNA and DNA?
- RNA uses Ribose as its sugar while DNA uses deoxyribose
- DNA uses base pairs A, G, C and T while RNA uses A, G, C, and U.
- RNA has a portion of genetic code stored not all of it but DNA has all of it
- RNA is typically single-stranded while DNA is typically double stranded
What is transcription?
The process by which DNA is converted into RNA.
RNA is polymerized similarly to DNA except it uses ____ ___________ instead of _____ __________.
uses RNA Polymerase instead of DNA polymerase
RNA is also synthesized in the __ to ___ direction.
5’ to 3’
The RNA transcript strand is the _____ of the DNA template strand meaning:
- compliment
- means that RNA transcript strand is identical to the DNA coding strand except you replace the T’s with U’s.
What is the promoter?
Area of code (of base pairs) that promotes transcription to occur. It always exists upstream from the Transcriptional Start Site (TSS).
What is the key line of base pair code that identifies the promoter region?
TATA
Strand is not important with RNA b/c it only copies __ strand of DNA and it will replace T’s with U’s so that changes the recipe.
-1
Because only one strand is copied, you must know which strand is the template strand. How do you determine this?
- Remember that it must encode from 5’ to 3’
- Remember that it must run anti-parallel to coding strand of DNA.
As mRNA is transcribed, it is in an immature form called ___-_____.
pre-mRNA
What modifications are made to convert pre-mRNA into mature mRNA?
- ways to tell mRNA apart from other forms of RNA
- prevent degradation
- transport mRNA to cytoplasm
- splice the required form
- stimulate translation
What is done to convert pre-mRNA to mature mRNA?
- 5’ capping (a chemical G pair cap is put on the 5’ end)
- 3’ polyadenylation (a bunch of A’s are put on the 3’ end)
- splicing occurs in the nucleus (co-transcriptional)
Do all of regions of coding sequence in pre-mRNA end up in its mature mRNA?
No!
What are the regions of coding sequence not included in mRNA called?
introns
What are the regions of coding sequence included in mRNA called?
exons
What is splicing?
The process of cutting out the introns and pasting the exons together.
What is responsible for splicing?
snRNP’s
How do snRNP’s splice?
2 snRNP’s will land on each side of the intron. They will then pull together and form a loop out of the intron. They then cut off the loop. It floats away and is destroyed. The remaining exons are now pasted together.
What is translation?
The process of using the nucleotide sequence of mRNA as a template to synthesize amino acids in the correct order to form a protein. (converting RNA into proteins)
What stores all the info for making proteins?
DNA
How does translation occur?
mRNA carries instructions coded by DNA during transcription to the ribosomes where the proteins that are coded for can be assembled.
What are the 3 types of RNA?
- mRNA
- tRNA
- rRNA
What does mRNA do?
serves as the template that brings the recipe for the protein coded in the DNA to the ribosome
What does tRNA do?
translates the message in the mRNA into an amino acid sequence
What does rRNA do?
associates with proteins to form the machinery needed to assemble proteins
How is the coding stored in mRNA for proteins?
In a sets of 3 nucleotides called codons
What is the purpose of a codon?
To correspond 3 nucleotides to a specific amino acid
What is the start codon?
AUG
How many codons are there?
64