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Unit 2 Test
Terms in this set (66)
UNWINDS -- In DNA replication, a protein that binds to DNA sequences called origins and unwinds parental DNA strands (double helix)
Helicase - What is it's role?
PRIMER -- In DNA replication, a protein that makes a short segment of RNA complementary to the DNA, a primer. It catalyzes the synthesis of short RNA primers, to which nucleotides are added to the template strand.
DNA Primase - What is it's role?
PROOFREADS + ADDS NUCLEOTIDES -- In DNA replication, DNA polymerase adds nucleotides to the 3' end of the growing strand; proofreads bases added + replaces incorrect Nucleotides.
-- DNA polymerase III - extends the strand in the 5'-to-3' direction; binds nucleotides to form new strands; enzyme adds DNA nucleotides to the RNA primer
-- DNA polymerase I - (exonuclease) degrades or removes the RNA primer and replaces it with DNA (inserts the correct bases; fills the gaps)
DNA Polymerase - What is it's role?
FILLS IN KNICKS -- In DNA replication, it joins the DNA fragments (Okazaki) into a continuous daughter strand; forms bonds (seals nicks) in sugar-phosphate backbone.
DNA Ligase - What is it's role?
UNWINDS + REWINDS -- In DNA replication, it unwinds before helicase and rewinds after ligase. Uncoils the "rope" by splicing through either one strand or both strands to release the tension. Gyrase (in bacteria)
Topisomerase - What is it's role?
Deoxyribonucleotides (A, T, G, C) can only be added to the 5' end of replicating DNA - True or False
False - to the 3' end
DNA Polymerase III can only synthesize new DNA in the 5' to 3' direction - True or False
Just one strand, called the lagging strand can be synthesized continuously - True or False
False - leading strand
DNA replication is semi-conservative - True or False
True - i.e., each strand of both replication forks is being copied
DNA replication is bidirectional - True or False
True - i.e., bidirectional DNA replication involves two replication forks, which move in opposite directions
The Central Dogma of DNA
replication (DNA) --> transcription --> RNA --> translation --> Protein
ACC (Originial DNA) What would be the new copy of DNA?
GTA (Originial DNA) What would be the new copy of DNA?
GGT (Originial DNA) What would be the new copy of DNA?
CGA (Originial DNA) What would be the new copy of DNA?
AAT (Originial DNA) What would be the new copy of DNA?
ACC (Originial DNA) What would be the new copy of RNA?
GTA (Originial DNA) What would be the new copy of RNA?
GGT (Originial DNA) What would be the new copy of RNA?
CGA (Originial DNA) What would be the new copy of RNA?
AAT (Originial DNA) What would be the new copy of RNA?
What is the "start" codon?
What are the "stop" codons?
UAA, UAG, UGA
is the sum total of genetic material of a cell
is a certain segment of DNA that contains the necessary code to make a protein, or an RNA molecule
-- Structural Genes - code for proteins
-- Genes - that code for RNA
-- Regulatory Genes - control gene expression
is the sum of all gene categories and constitutes an organism's distinctive genetic makeup
is the expression of the genotype created traits (eye color or height)
The Packaging of DNA: Winding, Twisting, and Coiling
Packaging the mass of DNA into the cell involves several levels of DNA structure.
Supercoils or Superhelices
In prokaryotes, the circular chromosomes packaged by the action of this special enzyme. This enzyme coils the chromosome into a tight bundle by introducing a series of twists into the DNA molecule.
Chromatin, creating a chain of these.
Structure in the packaging of DNA. Formed by the DNA strands wrapping around the histone protein to form nucleus bodies arranged like beads on a chain. One "bead" of the DNA chromatin and is approximately 11nm. This is the fundamental subunit of chromatin.
Inside the nucleus, DNA forms a complex with proteins called ____, which allows the DNA to be condensed into a smaller volume. When extended and looked at under a microscope, the structure resembles beads on a string.
proteins associated with eukaryotic DNA. These simple proteins serve as winding spools to compact and condense the chromosomes
composed of two copies each of the histone proteins H2A, H2B, H3, and H4.
the tightly coiled bodies in cells that are the primary sites of genes
contains approximately 3 billion based pairs packaged into 23 chromosomes; most cells in the body are diploid, with 23 pairs of chromosomes so total = 6 billion base pairs of DNA per cell. Each diploid cell contains about 2 meters of DNA
Haploid Human Genome
Copying DNA in the form of RNA
Main Idea of Transcription
region of DNA adjacent to the start of a gene
Sequence of DNA that binds RNA polymerase upstream of a gene
Sequence of bases at the end of a gene that signals the RNA polymerase to stop transcribing.
RNA polymerase binds to DNA and opens the double helix. It then recognizes the promoter which is rich in A's (Adenine) and T's (Thymine).
Transition Stage I - Initiation
RNA polymerase builds mRNA in the direction 5' to 3'. It uses only one strand of DNA to make it, called the template strand. The other strand is called the coding strand.
Transition Stage II - Elongation
RNA polymerase recognizes a terminator sequence telling it to stop transcribing at the end of a gene. Both mRNA and RNA polymerase are released.
Transition Stage III - Termination
The transcript (called the primary transcript at this stage) is then modified to prevent damage and degradation. A 5' cap is added at the 'top' which also helps in the initiation of translation. Similarly, a poly A tail is added to the opposing end which also helps in the termination of translation. Processes are known as capping and tailing.
regions of DNA that do not code for anything; do not allow the protein to fold and function properly which is why they are removed by spliceosome proteins; this results in a continuous coding region called the mRNA transcript
segments of DNA/mRNA that code for a specific protein
In the Northern Hemisphere occurs about June 21, when the sun is the highest. It is the longest day of the year.
1st American Woman in Space, 30th Anniversary
G = primary growth
S = genome is replicated Phase of Interphase in Cell Cycle
-- this is where the cell division process takes place
-- chromosomes replicate here
G2 = secondary growth
M = mitosis
Phases of Cell Cycle in Interphase
-- both DNA pieces are "cut" using the same restriction enzyme
* separates DNA everywhere where specific sequences are
* makes the ends of both pieces "sticky" (so they will pair up with each other)
-- the genes are put together and the sticky ends pair up to make one DNA piece
-- the recombined DNA is put into the bacterial cell (transformation)
-- the bacteria synthesize the protein coded for in the inserted gene
Steps of Gene Cloning
-- determining the order of the nucleotide bases in a molecule of DNA by inserting labeled DNA that cuts DNA into pieces based on size (uses electrophoresis)
* Predict the function of a gene
* Compare genes with similar sequences in different organisms
* Identify mutations in DNA
-- Cut DNA with an enzyme
-- Mix an unknown DNA fragment, DNA polymerase, and the four nucleotides
* Nucleotides are tagged with different colors and a different sugar that can't make a phosphodiester bond
-- DNA is copied by polymerase
* Each time modified nucleotide is added to the chain, it stops making the chain, breaking the DNA into pieces
* Sequence of DNA determines size pieces
-- Separate tagged DNA pieces by electrophoresis.
-- Analyze the segments with a computer
How to Sequence DNA
-- look different
-- control different traits
-- an inherent visual representation of chromosomes
-- 23 pairs
-- 46 chromosomes
• Chomosomes are composed of a complex of DNA and protein called chromatin that condenses during cell division
• DNA exists as a single, long, double-stranded fiber extending chromosome's entire length.
• Each unduplicated chromosoe contains a DNA...
• every 200 nucleotide pairs, the DNA wraps twice around a group of 8 histone proteins to form a nucleosome
• - cytokinesisnucleus
Structure of Chromosomes
mRNA = messenger in nucleus (scribe, stuck in tower writing recipes)
tRNA = transfer starts in cytoplasm takes to the ribosome (chef)
rRNA = ribosomal (speeds up the process or is a catalyst)
3 Types of RNA
translating RNA into protein
1. Splicing (introns and extrons)
3. End Tail (50-250 adedinine)
3 Steps of Modifying a Protein
20 necessary for life (8 are essential)
-- distinct from each other in their character
-- XY = male; XX = female
In order to have ____ you have to have:
-- RNA Polymerase
-- everybody has a unique sequence of bases in their DNA; like a fingerprint
-- Can be used to identify individuals from a tissue sample
-- because DNA sequences of family members have similar DNA, familial relationships can be identified with DNA
-- main method is Gel Electrophoresis
-- DNA is cut up into segments using restriction enzymes; separates DNA everywhere where specific sequences are
-- the DNA segments are put into a gel that has a charge that pulls the segments through the gel; smaller segments will move faster than larger ones leaving bands of DNA
-- if the DNA samples are from the same individual, their bands will be the same size and in the same place
-- Inside the nucleus, DNA forms a complex with proteins called chromatin, which allows the DNA to be condensed into a smaller volume
-- When the chromatin is extended and viewed under a microscope, the structure resembles beads on a string
* each of these tiny beads is a called a nucleosome
* diameter of approximately 11 nm
-- The nucleosome is the fundamental subunit of chromatin
-- composed of a little less than two turns of DNA wrapped around a set of eight proteins called histones, which are known as a histone octamer
-- Histone octamer is composed of two copies each of the histone proteins H2A, H2B, H3, and H4
-- The chain of nucleosomes is then compacted further and forms a highly organized complex of DNA and protein called a chromosome
Did you know that a nucleosome is a section of DNA that is wrapped around a core of proteins? (essay)
i = interference (purple petunia ---> white petunia)
Turn off genes by introducing genes that mimic viral shape (cop)
-- virus infect cells by inserting their DNA into the cells
-- cells synthesize its DNA along with its own
-- many viruses use double stranded, mirrored RNA
-- RNAi recognizes mirrored mRNA sequences and breaks them down
Long dsRNA molecules are cleaved to produce small interferring RNA (siRNA) by Dicer. siRNA molecules are then incorporated into a multiprotein RNA-inducing silencing complex (RISC). The duplex RNA is unwound leaving the anti-sense strand to guide RISC to complementary mRNA for subsequent endonucleolytic cleavage.
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