46 terms

DNA Study guide

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- How many chromosomes does a normal human cell have?
The normal human cell has 46 chromosomes.
- What is the difference between chromatin and chromosomes? When are they present and why?
A chromatin consists of DNA tightly coiled around proteins called histones, while a chromosome is condensed chromatin.
- What is the structure of DNA?
The structure of DNA is as follows: The sugar-phosphate frame is on the outside, then connected are the deoxyribose, with phosphate groups in-between. Connected to the deoxyribose are the nucleic acids, and in between the two is a hydrogen bond.
- What are the monomers of DNA?
The monomers of DNA are the nucleic acids. The nucleic acids are adenine, thymine, cytosine, and guanine.
- What is the difference between purines and pyrimidines?
Purines are either adenine or guanine, and they have 2 nitrogenous rings. A pyrimidine is either a cytosine or thymine, and they have only 1 nitrogenous ring.
- Why does a purine always pair with a pyrimidine? How does this ensure DNA's shape?
A purine bonds with a pyrimidine so that all of the pairs are 3 nitrogenous rings across.
- Compare and contrast the DNA of prokaryotes and eukaryotes.
Prokaryotes do not have a nucleus, while eukaryotes do have a nucleus.
- What type of bonds hold the two strands of DNA together? Why is that type of bond located there?
The weak hydrogen bonds hold the two bases together.
- How long is DNA? How does it fit inside a nucleus?
DNA is close to two meters long, but it fits inside the nucleus by wrapping itself around.
- What is DNA replication?
DNA replication is the process of replicating DNA.
- What are the steps of DNA replication?
The DNA strand breaks apart; the new base pairs come in with the new strand. DNA replicates to for DNA in a new cell.
- What enzymes are associated with the process of DNA replication?
The DNA polymerase is the principal enzyme associated with this process.
- When (under what conditions) and why does it take place?
DNA replicates for DNA in a new cell.
- Why is DNA replication called semi conservative?
DNA replication is known as semi-conservative because one strand is conserved, and another new one is made.
What did Griffith do?
Proposed that the ability to cause disease was inherited.
What did Avery do?
Determined that DNA was responsible for transformation.
What did Hershey and Chase do?
Determined that DNA was the genetic material.
What did Chargaff do?
Discovered that A=T and C=G
What did Wilkins do?
Helped Franklin with x-ray infractions.
What did Franklin do?
Used x-ray infraction to help determine the structure of DNA.
What did Watson and Crick do?
Built 3D models to study the structure of DNA.
Pneumonia
virus and bacteria caused lung infection.
Bacteriophage
virus that can infect bacteria, but has no effect on humans, which is why they were beneficial in the Hershey and Chase experiment; means "bacteria - eater"
Transformation
process in which one strain of bacteria is changed by a gene or genes from another strain of bacteria. Process discovered by Griffith in his experiment of smooth/ harmful and rough/harmless pneumonia bacteria.
Genetic Information
DNA
Nucleotide
Monomer of nucleic acids made up of a 5-carbon sugar, phosphate group, and nitrogenous base
Phosphate group
A functional group or radical comprised of phosphorus attached to four oxygen, also part of the backbone of DNA with the 5-carbon sugar
Nitrogenous bases
includes the purines and pyrimidines, on the inner side of DNA, A nitrogen-containing molecule having the chemical properties of a base.
How long is DNA?
2 Meters
Okazaki Fragments
short molecules of single-stranded DNA that are formed on the lagging strand during DNA replication.
Prokaryotes
single celled organism; no nucleus; DNA in cytoplasm- only 1 strand
Eukaryotes
complex organisms with nuclei; 1000x more DNA than prokaryotes; DNA found in Nucleus
Chromatin
consists of DNA that that is tightly coiled around proteins called histones; granular material visible within the nucleus
Chromosome
threadlike structure within the nucleus containing the genetic information that is passed from one gen of cells to the next
Purine
Have two rings in their structures
Pyrimidine
Have one ring
Helicase
The enzymes in DNA that pushes the strain apart in to 2
DNA polymerase
Enzyme that "proofreads" new DNA strands, helping to ensure that each molecule is a nearly perfect copy of the original DNA
Ligase
Glues the spaces back together in DNA replication
Eukaryotes
As many as 1000 times the amount of DNA as prokaryotes found in nucleus as chromatin
Histones
Globular protein molecule around which DNA is tightly coiled in chromatin
Prokaryotes
Lack nuclei
Chromatin
Visible within the nucleus; consists of DNA tightly coiled around proteins (pasta)
Chromosome
Threadlike structure within the nucleus containing the genetic information that is passed from one generation of cells to the next
Basing pair rule
adenine and thymine, guanine and cytosine
Bacteriophage
virus that can infect bacteria, but has no effect on humans, which is why they were beneficial in the Hershey and Chase experiment; means "bacteria - eater"
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