How can we help?

You can also find more resources in our Help Center.

32 terms

Molecular Basis of Inheritance

Chapter 16
STUDY
PLAY
Chromosomes
reside in nucleus. present in pairs. made of DNA and proteins. Homologs (pairs) separate during meiosis.
Gene
A funtional segment of DNA located at a certain point (locus) on a chromosome;codes for a protein.
DNA
found in nucleus. carries hereditary information. Consists of 4 nucleotides (contains a 5 carbon deoxyribose sugar, a phosphate and a Nitrogen base) 4 different nitrgoen bases.
DNA nucleotides
contains a 5 carbon deoxyribose sugar, a phosphate and a nitrogen containing base.
4 nitrogen bases
Thymine, Cytocine, Adenine and Guanine
Pyrimidine Bases
have single rings. Thymine and Cytosine.
Purine Bases
have double rings. Adenine and Guanine
Alfred Mirsky
worked with protein structure. helped prove that DNA must be the holder of hereditary information.
Erwin Chargaff
discovered that base composition of DNA varies from one species to another. But DNA always has equal amounts of Adenine and Thymine and equal amounts of Guanine and Cytosine.
Rosalind Franklin and Maurice Wilkins
Bombarded DNA with x-rays to form a picture. determined that DNA was helical, has repeating subunits, and had a sugar-phosphate backbone.
James Watson and Francis Crick
published structure of DNA. built the double helix model.
antiparallel
the two DNA nucleotides run in opposite directions.
replication
one DNA strand is copied to produce 2 identical strands
Conservative Replication
A possible model of replication. 2 parental strands act as templates for 2 new strands then reassociate. This was determined to be false.
Semi-Conservative Replication
A possible model of replication. 2 parental strands act as templates for 2 new strands. Each replicated helix contains one "old" strand and one "new" strand. This was determined to be true by Messelson and Stall.
Dispersive Replication
A possible model of replication. Daughter strands are composed of old and new DNA pieces.
Origin of Replication
replication begins here.
Replication Bubble
the open area that is made when DNA begins separating for replication.
Antiparallel Elongation
DNA can only be replicated in a 5 prime to 3 prime direction.
Okazaki Fragments
to replicate "backwards", pieces on the lagging strand are made in the 5 prime to 3 prime direction and those pieces are called...
Helicase
"unzips" DNA.
Topoisomerase
works ahead of the helicase to relieve tension on the double helix. It does this by cutting the sugar-phosphate backbone, swiveling it and reattaching it.
Single-Strand Binding Proteins
stabilizes the template DNA so they do not reattach.
Primase
adds RNA primer to strands so DNA bases can be added to make the new DNA molecule.
RNA Primer
leading strand only needs one primer from the origin of replication. Lagging strand needs a new primer for each Okazaki Fragment.
DNA Polymerase III
attaches nucleotides to form the new DNA strand.
DNA Polymerase I
removes the primer and adds one or more nucleotides.
DNA Ligase
links sugar phosphate backbone of the Okazaki Fragments together.
Proofreading Enzymes
proofread the DNA. 130 types identified in humans. 1 in 100,000 are mispaired and then corrected. DNA polymerases also double check base pairing.
Telomeres
Repeated DNA sequences at the ends of eukaryotic chromosomes.
TTAGGG
humans have this repeated 100-1000 times at the ends to protect the ends of the DNA. carries no genetic information. is just there to protect the ends.
Telomerase
this enzyme lengthens the telomeres back to their original length.