a
What are the 3 kinds of RNA?
mRNA: a complementary copy of a gene
rRNA: part of the ribosome
tRNA: carries amino acids for polypeptide assembly
Where does initiation of transcription occur?
at the promoter, a sequence of DNA that indicates where a gene begins and which strand is the template, at the initiation site
What is the wobble effect?
For many AA, the 3rd base of the codon can vary (degeneracy or wobble)
These codons are recognized by the same codon
What is the cell division process found in prokaryotes?
binary fission
What is the central dogma of biology? include the processes used
DNA -> transc -> RNA -> transl -> protein
What is the difference between monosomi and trisomi?
Monosomic: one version of chromosomes in a diploid zygote
Trisomic: three versions of a chromosome in a diploid zygote
What are the 2 processes involved in expressing a gene to form a polypeptide & what happens?
Transcription: copies information from gene (DNA) to a sequence of DNA; “rewrite in the same language”
Translation: converts RNA sequence into amino acid sequences of a polypeptide; “rewrite in a different language”
What does it mean for DNA to be complementary, antiparallel, and a double helix?
1) complementary = A-T & C-G
2) antiparallel = 5-3 & 3-5
3) double helix = 2 strands make 1 molecule
What is the difference between somatic and gamete cells?
Somatic cells: body cells, diploid (2n), Have 2 versions of each chromosome
Gametes: eggs and sperm; haploid (1n), Have 1 version of each chromosome
N means number of chromosomes
Egg (1n) + sperm (1n) = human (2n)
Both transcription and translation have the same 3 steps involved, just with different ways they go about them.
What are these 3 steps?
initiation, elongation, termination
What is the difference between prokaryotic and eukaryotic chromosomes?
I can think of 4!
1. circular vs linear
2. continuous vs. beginning and ends
3. DNA + binding proteins vs chromatin (DNA+histones)
4. in nucleoid vs nucleus.
What are the products of mitosis and meiosis?
mitosis: 2 diploid somatic cells that are genetically identical
meiosis: 4 haploid gamete cells that are genetically diverse
In meiosis, what separate during M1 and M2? How similar or different are these to mitosis?
meiosis I: separate homologs (unique to meiosis)
meiosis II: separate sister chromatids (very similar to mitosis)
given the DNA molecule,
3'-GCC-5'
5'-CGG-3'
What is the template strand? what is the lagging strand?
template strand: 3'-GCC-5'
mrna strand : 5'-CGG-3'
What are 3 DNA repair methods and when do they take place?
Proofreading: DNA poly corrects errors during replication (during rep)
Mismatch repair: proteins remove the incorrect base and replace with the correct base (after rep)
Nucleotide excision repair: corrects damaged bases (after rep)
Starting at nucleotides, name the order of structures leading to creating a chromosome
I'm thinking of 7 things!
nucleotides < gene < DNA < nucleosome < chromatin < chromatid < chromosome
What are telomeres and telomerase? How are they connected?
telomeres are the ends of a chromosome that get shorter with each subsequent cell division.
telomerase is an enzyme found in stem cells that rebuilds the lost telomere sections during replication.
In eukaryotes, what are the 3 mRNA processing methods used before translation can occur? What do these modifications do?
Step 1: splice out introns, put exons together
Introns = non coding sequences; exons = coding sequences
Introns must be spliced/cut out of the pre-mRNA
Step 2: ends of pre-mRNA are modified
5’ end: a modified guanine (5’ cap) is added
Helps mRNA bind to ribosome
Protects mRNA from being digested outside of the nucleus
3’ end: a poly-A tail (100-300 adenines in a row) is added
Assists mRNA in leaving the nucleus
Protects mRNA from degradation
What are 2 methods used in meiosis to increase genetic variation? When do they occur?
Crossing over (P1) - chromosomes with genes from both parents
Independent assortment (M1)- randoms way that chromosomes line up
In translation, how do tRNAs move through a ribosome? what happens at each site?
Large subunit has three tRNA binding sites
A site: Anticodon of charged tRNA binds
P site: tRNA binds its amino acid to polypeptide chain
E site: tRNA exits ribosome
A > P > E; Bind > attach > leave
(happens right to left)
compare and contrast initiation, elongation, and termination in transcription and translation
transcription vs. translation
initiation: RNA poly binds to promoter region on DNA vs. SSR attaches to mRNA start codon
elongation: RNA poly unwinds DNA + mRNA built 5'-3' vs. tRNA binds to codons + builds polypeptide
termination: RNA poly releases at the terminator sequence vs. protein release factor binds to stop codon
Give the contributions made by each scientist to DNA structure.
1. Rosalind Franklin
2. Erwin Chargaff
3. Linus Pauling
4. James Watson
5. Francis Crick
Rosalind Franklin = X-ray crystallography of pure, crystalized DNA showed a very unique pattern
Erwin chargaff = #A = #T ; #C = #G
Linus Pauling = 3D model of molecules
James Watson and Francis Crick = integrated everyone’s work to determine the structure of DNA
In a DNA molecule,
5'-ATCG......-3' (helicase)
3'-TAGC......-5'
Which strand is the template for the leading strand? for the lagging strand? explain.
3'-TAGC......-5' is the template to the leading strand
5'-ATCG......-3' is the template for the lagging strand
This is because of the orientation of the strands in relation to helicase. Because nucleotides are synthesized in the 5'-3' direction, a lagging strand will be produced on the strand in the 5'-3' direction.
Explain the cell cycle
Gap 1 (G1): The cell increases in size
Synthesis (S): The cell copies its DNA
Gap 2 (G2): The cell prepares to divide
Mitosis (M): The cell divides
G1 + G2 + S = interphase
Functions of:
1. Helicase
2. Primase
3. DNA pol III
4. DNA pol I
5. Ligase
Helicase: Unwinds DNA