Exam 1: Prior to Hw 8/26

Question 1

What is the chromosomal theory of inheritance?

Answer 1

Genes for phenotypic traits are carried on chromosomes.

Question 2

What is a gene?

Answer 2

A gene is section (sequence) of DNA that codes for a gene product.

Question 3

What is a variant?

Answer 3

A variant is the same section of DNA with different sequences.

Question 4

What is an allele?

Answer 4

An allele is a specific variant that codes for a specific gene product

Question 5

What is a genome?

Answer 5

A genome refers to all of the coding and noncoding DNA of an organism

Question 6

Human genome vs Individual genome

Answer 6

Human genome: refers to the most commonly occurring sequences and orders.
Individual genome: sequences/traits particular to an individual

Question 7

What are the five subdisciplines of Genetics, and what do they focus on?

Answer 7

1) Transmission Genetics: Mendelian, classical; basic differences; how traits are passed down to offspring from parents

2) Molecular Genetics: the structure and function of genes

3) Genomics: the analysis of genomes (all of the coding and sequences), the sequencing of DNA; Genome Wide Association Study (GWAS)

4) Population Genetics: the study of traits determined by one (or a few) genes in groups of individuals

5) Quantitative Genetics: the study of complex traits (meaning influenced by many genes (polygenic) and the environment)

Question 8

What two major approaches do geneticists use?

Answer 8

Forward Genetics: identify a gene(s) controlling a phenotypic trait (ie. CFTR gene - cystic fibrosis)
Reverse Genetics: discover gene function after a gene has been identified

Question 9

Transmission Genetics

Answer 9

Mendelian, classical; basic differences; how traits are passed down to offspring from parents

Question 10

Molecular Genetics

Answer 10

the structure and function of genes

Question 11

Genomics

Answer 11

the analysis of genomes (all of the coding and noncoding sequences), the sequencing of DNA; Genome Wide Association Study (GWAS)

Question 12

Population Genetics

Answer 12

the study of traits determined by one (or a few) genes in groups of individuals

Question 13

Quantitative Genetics

Answer 13

the study of complex traits (meaning influenced by many genes (polygenic) and the environment)

Question 14

What must be the functions of genetic material?

Answer 14

1) Must contain information about the organism’s cell structure, function, development, and reproduction.

2) Must be able to be expressed and used in above mentioned functions.

3) Must replicate accurately so that progeny (children) cells have the same information as the parent cells.

4) Must be capable of change (adaptation and evolution would not occur otherwise)

Question 15

What is a basic difference between DNA (deoxyribonucleic acid) and RNA (ribonucleic acid)?

Answer 15

DNA has no hydroxyl group on the 2’ carbon, while RNA does

Question 16

What organisms most commonly carry DNA and which carry RNA?

Answer 16

DNA: All prokaryotes, eukaryotes, and a few viruses have dsDNA as the genetic material
RNA: Many viruses have RNA as their genetic material

Question 17

Who published the model of the DNA structure and won a Nobel Prize in 1962 for this description of DNA?

Answer 17

Watson and Crick (plus others)
-Designed a molecular structure of DNA based upon:
1) Polymer of nucleotides containing a five-carbon sugar (ribose), nitrogenous base, and phosphate group
2) Chargaff’s Rule
3) Rosalind Franklin’s X-ray diffraction data
4) Their of knowledge of chemistry (bonding potentials, bond lengths/angles, repulsive forces, etc.)

Question 18

What carbons are the phosphate and nitrogenous bases attached to in a nucleotide?

Answer 18

Phosphate is attached to the 5’ carbon of the 5-carbon ribose sugar, while the nitrogenous base is attached to the 1’ carbon of the 5-carbon ribose sugar through a glycosidic bond.

Question 19

Nucleoside vs Nucleotide

Answer 19

A nucleoside contains a sugar and a nitrogenous base, while a nucleotide contains a sugar, nitrogenous base, and a phosphate.

Question 20

What are the nitrogenous bases? And which ones are purines and which are pyrimidines?

Answer 20

Pyrimidines: Cytosine, Uracil, Thymine
Purines: Guanine and Adenine

Question 21

What is Chargaff’s Rule?

Answer 21

The ratio of nitrogenous base pairs A:T and G:C was always ~1; however, the amounts of total AT and total GC bases could differ among species.

Question 22

Franklin and Wilkins concluded that DNA was what two things?

Answer 22

1) DNA is helical
2) DNA has distinct periodicities along the helix: 3.4 nm = 360 degrees
0.34 nm = space between bases
About 10 base pairs per turn

Question 23

How are nucleotide subunits connected?

Answer 23

They are connected by a phosphodiester bond.

Question 24

What are the characteristics of B-DNA?

Answer 24

1) Sugar-phosphate “phosphodiester backbone”
2) Bases on inside
3) Right-handed helix
4) Major and Minor groove
-caused by the angle of the glycosidic bonds
-proteins recognize the sizes of the grooves and molecular interactions like H bonding potentials

Question 25

Why is the major groove more readily bonded to?

Answer 25

The major groove has more features to bond to and recognize.

Question 26

B-DNA has antiparallel arrangement, what does this mean?

Answer 26

Antiparallel arrangement is when two strands have opposite directionality (also referred to as polarity) and is like a two-lane highway.

Question 27

3 characteristics of RNA?

Answer 27

1) Has a hydroxyl group (OH) at the 2’ carbon
2) Contains uracil instead of thymine
3) Genetic material for some viruses

Question 28

3 characteristics of DNA?

Answer 28

1) Has a H instead of an OH at the 2’ carbon
2) Contains thymine
3) Is the genetic material for all known prokaryotes and eukaryotes

Question 29

What characteristics must a molecule have that serves as genetic material?

Answer 29

1) The ability to be replicated
2) The ability to store information
3) The ability to express stored information
4) The potential to be changed via mutation

*Does not have to directly influence the development of traits

Question 30

True or False
dNTPs are used during DNA synthesis

Answer 30

True

Question 31

True or False
These equations follow Chargaff’s Rule:
(A + G) = (C + T)
(A + C) = (G + T)
A = T
(A + G) / (C + T) = 1

Answer 31

True

Question 32

The melting temperature (Tm) of dsDNA is influenced by what?

Answer 32

1) The length of the DNA
2) The GC content of the sequence
3) The total number of hydrogen bonds between the base pairs of the sequence

Question 33

How many hydrogen bonds do adenine (A) and thymine (T) have, and how many do cytosine (C) and guanine (G) have?

Answer 33

Adenine and Thymine share 2 hydrogen bonds, while Cytosine and Guanine share 3 hydrogen bonds.
Which makes cytosine and guanine have the stronger bond, hence why the melting temperature is higher for a C-G pairing than an A-T pairing.

Question 34

What is the (2+4) Rule?
Demonstrate by solving the Tm of this dsDNA sequence.
5’ -ATG-GAC-CCG-ATT-TAT-3’

Answer 34

2(A + T) + 4(C + G) = Tm
5’ -ATG-GAC-CCG-ATT-TAT-3’
Tm = 2(4 + 5) + 4(3 + 3)
= 2(9) + 4(6)
= 18 + 24
= 42 degrees Celsius

Question 35

If each 360 degree turn of the double helix contains approximately 10 base pairs, how many nucleotides are there?

Answer 35

10 base pairs = 20 bases
1 nucleotide contains 1 base
20 nucleotides are found within one 360 degree turn of the double helix.

Question 36

Any two nucleic acid fragments will spontaneously hybridize if they encounter each other as they are what two things?

Answer 36

As long as they are complementary and antiparallel.

Question 37

Considering the structure of double-stranded DNA, __________ bonds hold one complementary strand to the other.

Answer 37

hydrogen