Genetics Exam 3

What are nucleic acids?

DNA and RNA

What are nucleotides and what are they composed of?

the repeating structural unit of DNA and RNA; they are composed of a phosphate group, pentose sugar and a nitrogenous base

What is a nucleoside?

Base+sugar

ex: adenine+ribose

What is the composition of a chromosome?

single molecule of DNA coiled tightly around histones

What sugar is found in RNA?

ribose

What sugar is found in DNA?

deoxyribose

What is a purine?

5 and 6 membered rings

ex: adenine and guanine

What is a pyrimidine?

six membered rings

ex: cytosine, thymine and uracil

In linear DNA, what are functional groups you would expect to see at the free 5’ and 3’ ends?

5’ ends with phosphate group and the 3’ end has a hydroxyl group

How are adjacent nucleotides linked to each other?

What are Chargaff’s rules of base composition?

percent of adenine= percent of thymine

percent of cytosine= percent of guanine

How did Franklin play a role in the discovery of DNA?

obtained several structural features of DNA such as the shape (helical), it is more than one strand and has 10 base pairs per complete turn.

How did Wilkins play a role in the discovery of DNA?

pioneered xray defraction and produced high DNA images and shared them with Watson and Crick

How did Watson and Crick play a role in the discovery of DNA?

created a ball-and-stick mode, realized that the bonding of the adenine to thymine bonding was similar to cytosine to guanine bonding.

What is the proposal Watson and Crick proposed about the double helix?

there are 10 base pairs, the strands are antiparallel and the helix is right handed

What is the width of common form of DNA?

2nm

What are the features of the major groove?

much bigger than the minor groove

What are the features of a minor groove?

smaller than the major groove

Where do DNA binding proteins bind?

to specific DNA sequences in the major groove

What do DNA binding proteins interact with?

DNA sequences

What are the two important implications of DNA structure?

Z DNA and B DNA

What are the dimensions of Z DNA?

left handed helix

alternating purine/pyrimidine sequences at high salt conc.

cytosine methylation at low salt concentrations

negative supercoiling

What is the number of base pairs per turn in Z DNA?

12bp per turn

What is the number of base pairs per turn in B DNA?

10bp

What are the dimensions of B DNA?

right handed helix

How is the RNA structure different than the DNA structure?

What are the factors that contribute to the tertiary structure of RNA?

base pairing and base stacking within the RNA itself

interactions with ions, small molecules and large proteins

What is the biochemical composition of chromosomes?

What are the characteristics of a chromosome of a prokaryote?

What are the characteristics of a chromosome of a eukaryote?

How many origins of replication per circular chromosomes are found in prokaryotes?

What is a genome?

What are the two genomes found in an animal cell?

What are the three genomes found in a plant cell?

The genetic material produces the ________ of an organism mainly through _________ encoded by ___________.

What are the various functions of DNA sequences?

How many sets of chromosomes are seen in eukaryotes?

In humans, how many sets of chromosomes are found? How many chromosomes are found in each set?

What is the range of nucleotides found in different human chromosomes?

Why are genes longer in flowering plants and mammals as compared to yeast?

What are some functions/features of an origin of replication?

What are some functions/features of a centromere?

What are some functions/features of a telomere?

What are some functions/features of a CTCF binding site?

What protein binds the DNA at the centromere?

How frequently along the chromosome are the origins of replication distributed in eukaryotes?

Where are repetitive sequences found along chromosomes?

What are some possible reasons for variation in genome size but not in complexity?

How are repetitive sequences classified into three major categories?

What fraction of the genome is composed of unique sequences?

What fraction of the genome is composed of non-repetitive sequences?

What are some characteristics of the Alu family of highly repetitive sequences?

Other than the Alu family where else in the genomes are highly repetitive sequences are found?

What is a nucleosome?

What are the characteristics of a nucleosome?

What kind of amino acids are commonly found in histones?

How do amino acids help histones bind to DNA?

How many base pairs of DNA are wound around the histone octamer?

What is a typical structure of a histone protein?

RNA double helices have what characteristics?

right handed

have 11-12 base pairs per turn

How many RNA molecule structures are there and what are they?

4

bulge loop, internal loop, multibranched loop, and stem loop