18.1- DNA structure and replication Flashcards
DNA controls ____
heredity
Hereditary info is carried through ___ on ____
genes on chromosomes
how Is cell structure and function controlled
through DNA controlling protein synthesis
RNA is involved in
gene expression
who came up with the transforming principle
Frederick griffith
what was the transforming principle
dead pathologic bacteria could pass on the disease causing capabilities to live bacteria- live bacteria- were “trasnformed”
what did Hershey and chase use
they used radioactive labeling to trace hereditary material of a virus
Both DNA and RNA are made up of small subunits called ___
nucleotides
DNA bases =
Adenine (A)
guanine (G)
Cytosine (C)
Thymine (T)
RNA bases =
Adenine (A)
guanine (G)
Cytosine (C)
Uracil (U)
A + G are called ___
Purines
C + T/U are called ___
pyridamines
What is chargaffs rule
A pairs with T
C pairs with G
(Purines pair with pyridamines)
what did Rosalind Franklin do/discover (2)
- Used x-rays to study the shape of DNA
- Discovered that DNA has a helical structure with sugar phosphate backbone on the outside and bases on the inside
what did Watsin and Crick do
- produced a model of DNA structure
describe the double helix structure of DNA
2 nucleotide strands (connected by H-bonds) twisted into a helical shape
Nucleotide strands are ___ to each other
antiparallel (flipped)
Genome=
The entire set of DNA found in each cell
Genetic code is made up of ___
a specific sequence of nucleotides
DNA can make exact copies of itself during what phase
The S phase of interphase
what is the S phase
DNA synthesis (copy)
3 stages of DNA replication
1- Initiation
2- Elongation
3- termination
what happens during the initiation stage of DNA replication (3)
- begins at replication fork
- Helicase enzymes bind to replication origin and cause DNA to unwind/unzip
- unzipped strands act as templates for new strands to build from
what happens during the elongation stage of DNA replication (4)
- Enzyme DNA polymerase nucleotides are added to 3’ end of chain
- leading strand is replicated continuously from 5’ end to 3’ end
- lagging strand is replicated in many short segments (okazaki fragments)
- newly replicated segments return to double helix
what happens during the termination stage of DNA replication (1)
when both strands of DNA are completely replicated they separate and the replication machine breaks down
what makes up the replication machine
many enzymes and proteins involved in the replication fork
what enzymes cause DNA to unwind/unzip
Helicase
What does DNA Ligase do
links okazaki fragments together into a continuous chain
what provides a starting point for DNA polymerase
RNA primer
What does DNA polymerase do and what stage of DNA replication is it involved in
- It proofreads to sequence and makes sure H-bonding is happening between complementary bases
- Elongation stage
What Sugar does DNA use
deoxyribose
what Sugar does RNA use
Ribose
RNA uses ___ instead of thymine as a _____ base
Uracil
nitrogenous base
is RNA single stranded or double stranded
Single stranded
