Chapter 8: The Structure, Replication, and Chromosomal Organization of DNA Flashcards
Who first purified nuclei from cells in the 1860s?
Friedrich Miescher.
The contents of the nuclei contained a substance he called nuclein
What were identified as the carriers of genetic information in early 1900s?
Chromosomes
Which scientists proved that DNA is the transforming factor between bacterial strains?
Griffiths and Avery, MacLeod, and McCarty
Who proved that DNA is the genetic material in viruses?
Hershey and Chase
What carries genetic information?
DNA not proteins
Which type of virus kills bacteria?
Bacteriophages
What are Bacteriophages made of?
Made up of only a protein coat and DNA
How do Bacteriophages kill bacteria?
DNA enters bacterium, protein coat stays outside
Name this bond
single covalent bond
Name this bond
double covalent bond
Name this bond
hydrogen bond
Nucleotides are joined by covalent bonds to form what chains?
polypeptide chains
What are the three components of nucleotide building blocks?
- Nitrogen-containing base
- Purines (A and G)
- Pyrimidines (C and T) - Sugar
- Deoxyribose - Phosphate group
Name this structure
Adenine (A)
Name this structure
Thymine ( T ) (in DNA)
Name this structure
Uracil (U) (in RNA)
Name this structure
Guanine (G)
Name this structure
Cytosine (C)
Name this structure
Deoxyribose (in DNA)
Name this structure
Ribose (in RNA)
Name this structure
Phosphate group
In the DNA double helix, where are the phosphate groups located?
phosphate groups on the outside of the helix
In the DNA double helix, where are the bases located?
bases stacked inside the helix
How is the DNA twisted ladder confirmation described?
- Two polynucleotide strands (“rails”), held together by hydrogen bonding between the bases (“rungs”)
- The strands are oriented in opposite directions
In DNA, base A pairs with
T
In DNA, base G pairs with
C
The two polynucleotide chains in DNA run in what direction?
opposite direction
Where is genetic information stored in DNA?
Four bases allows for a high coding capacity
What is the complete set of genetic information for a given organism?
its genome; genome size is species-specific
Any change to the linear sequence of DNA that can result in an altered phenotype is called a
mutation
Complementary sequence of the two strands explains how DNA can be
replicated
What type of bonds joins nucleotides in RNA to form polypeptide chains?
covalent bonds
Is RNA single-stranded?
yes, folds upon itself
What is the function of RNA?
Transfer of genetic information from the nucleus to the cytoplasm, protein synthesis, and gene expression
Term describing how each daughter molecule receives one old DNA strand and one newly synthesized DNA strand in DNA replication?
Semiconservative replication.
Both strands serve as templates for synthesis of a new, complementary strand
Which direction does DNA proceed in replication?
Proceeds in a 5’ to 3’ direction
In which phase of the cell cycle does DNA replication occur?
S phase in the cell cycle
What creates a template for the synthesis of a new DNA strand in replication?
The two polynucleotide strands uncoil.
Why is three-dimensional structure of chromosomes is important?
- ~2m of DNA must fit inside a nucleus with a 5μm diameter
- Chromosomes uncoil and recoil during the cell cycle
- Spatial arrangement of DNA is important for the regulation of gene expression
Within chromosomes, DNA is coiled around clusters of what?
histones to form nucleosomes
How does a genome fit inside a nucleus?
extensive coiling
What are short, repeated sequences at chromosome tips?
telomeres
During DNA replication, some repeats of telomeres are left uncopied, leading to
shortened telomeres with each cell division
What defines the spindle attachment site?
Centromeres
What does the location of the centromere contribute to?
the unique shape of any given chromosome
Chromosomes are located in
Specific territories in the nucleus. Chromosome territories are linked to function.
