Molecular Genetics Flashcards
Where did nucleic acids get their name?
They are weak acidic material that is isolated from the nucleus.
What are two types of nucleic acid?
DNA= deoxyribonucleic acid and RNA=ribonucleic acid
What was the Griffith experiment?
Mouse studies
What did Griffith find out regarding hereditary information?
Hereditary information is passed down from dead bacterial cells to live bacterial cells which turn the live cells from harmless into a disease causing form.
What did Rosalind Franklin picture with her experiment?
She experimented with x-ray crystallography to study the structure of DNA.
What was Avery, Macleod and McCarthy’s experiment?
They refined Griffith’s experiment to show that DNA and not proteins were the hereditary material in bacteria.
What was the Hershey/Chase experiment?
Experimented with a bacteriophage (a virus that infects bacteria) on bacteria to find that DNA and not protein is the transferred hereditary information. They used radioactive taggers.
What three things did Linus Pauling propose?
- The secondary structure of proteins is an alpha helix shape.
- The DNA is a helix structure.
- The DNA is a triple helix.
What did Watson and Crick figure out with Franklin’s picture?
They figured out the double helix structure of DNA.
What is Meselson and Stahl’s experiment? What did they discover?
They discovered the semi-conservative nature of DNA by using isotope nitrogen 15 on the original DNA of bacteria culture. As the bacteria reproduced, the glow of the nitrogen-15 dimmed.
Who was the first to make a model of DNA?
Watson and Crick
Where is DNA found in plants? (3)
Nucleus, mitochondria, and chloroplast.
Where is DNA found in humans? (2) Which parent passes down each DNA?
Nucleus and Mitochondria. Nuclear DNA is passed down by both parents. Mitochondrial DNA is passed down by the mother only.
What is the backbone of a DNA molecule made of?
Sugar and phosphate.
What does a nucleotide consist of?
One set of sugar, base, phosphate.
What are attached to the sugars in DNA?
Nitrogenous bases.
What type of bonds connect the nucleotide?
Covalent bonds.
How many carbons compose the sugar molecules in a DNA molecule?
5 carbon sugars
What type of bond connects the nitrogenous bases of different strands of DNA?
Hydrogen bonds.
Name two types of bases and describe each one.
Purines are double ring structures. (A and G). Pyrimidines are single ring structures (T and C).
What ae the two complementary base pairs?
Adenine with Thymine. Guanine with cytosine.
What did Chargoff find?
He found that A and T and G and C bases are found in equal amount.
Draw a nucleotide and a DNA molecule.
Whose experiment showed that bases are on the inside of DNA and sugars and phosphates are on the outside?
Franklin’s Experiment
What do you call the fact that DNA strands compliment each other?
Antiparallel
What are the two prime ends to strands of DNA?
A 5 prime strand and a 3 prime strand.
What is the sugar in DNA called? RNA?
Deoxyribose. Ribose.
What nitrogenous base is replaced in RNA? With what?
Uracil (U) replaces thymine (T).
What are the three types of RNA? What do they stand for?
mRNA = messenger RNA. tRNA = transfer RNA. rRNA = ribosomal RNA
How many strands is RNA?
One
What is a structural gene?
A section of DNA that is on a chromosome and encodes for one or more proteins.
What is a gene?
A heritable factor that consists of a length of DNA and influences a specific characteristic.
What type of DNA do prokaryotes have?
Circular DNA
What is the human genome project?
The entire base sequence of human genes.
How do alleles differ from each other DNA wise?
They only differ by one or a few bases.
How are new alleles formed?
By mutation.
What is DNA wrapped around?
Histone which is a protein.
What is DNA wrapped around histones called?
Nucleosomes.
What do nucleosomes coil into? What happens after that?
Chromatin Fibre. Further condensation of chromatin happens.
What does a chromatin form?
A chromosome.
What is the difference between a chromatin and a chromatid?
A chromatin forms DNA while a chromatid is one strand of chromosome.
What is the Cairn’s technique for? How does it work?
The Cairn’s technique is for determining the length of DNA. Cells are grown in radioactive thymine. The cells are lysed to isolate the chromosomes. The chromosomes are placed on a photographic surface and rinsed with radioactive sensitive silver bromide emulsion. The silver ions stick to the radioactive thymine and this appears black when film is developed.
What has to happen to DNA in order for cells to divide?
DNA must replicate
Wat are helicases? Where do helicases bind? What is its purpose?
Helicases are enzymes that bind to DNA at the replication origin and break the H-bonds between the two DNA strands in order to unravel the segment.
What is the specific part of the DNA sequence where replication starts called? How many per strand?
Replicon. Can have many per strand.
What is a replication bubble? What is a replication fork?
A replication bubble is an unwound open area of a bubble. A replication fork is the y-shaped area at each end of a replication bubble.
What does semiconservative mean in regard to DNA?
Each replicated strand of DNA contains one original strand (parent strand) and one new strand (daughter strand).
What must cells have in order to replicate DNA? Where does that come from?
Nucleotides which come from the food we eat.
What are single strands in a bubble used as?
A template for new DNA.
Does replication take place at one location at a time?
No, it takes place at several locations at one time.
What binds to DNA to keep the two strands separate?
Proteins
What is the starting point for DNA Polymerase III to add its nucleotides called?
An RNA primer.
What adds complementary nucleotides in the 5’ to 3’ direction?
DNA Polymerase III
What is elongation?
The process of creating a new strand of DNA.
What are the leading vs lagging strand? How are each synthesized?
The leading strand is the one going from 5’ to 3’ and it is synthesized continuously. The lagging strand is the one going from 3’ to 5’ and it is synthesized in short fragments called okazaki fragments.