lect 13: genes and the genome I

Question 1

what is the graph of the history of discoveries of DNA?

Answer 1

Question 2

what are the learning objectives of this lecture?

Answer 2

-brief history of the discovery of DNA

DNA structure
-watson-crick proposal
-DNA structure provides a mechanism for heredity

chromosome structure
-levels of chromosome organization
-specialized nucleotide sequences

Question 3

what are mendel’s laws of inheritance?

Answer 3

Question 4

what is a gene?
a) a unit of a chromosome
b) a unit of inheritance
c) a unit of DNA
d) all of the above

Answer 4

b) a unit of inheritance

Question 5

the law of independent assortment states that _____________
a) segregation of an allelic pair for one trait has no effect on segregation of alleles for another trait
b)an organism’s two alleles for a gene separate from one another during gamete formation
c)segregation of an allelic pair for one trait has a great effect on segregation of alleles for another
d) an organism’s three alleles for a gene separate from one another during gamete formation

Answer 5

a

Question 6

what were key contributions to DNA’s discovery?

Answer 6

didn’t know about DNA until 1870

Question 7

DNA structure needed to explain two things…..

Answer 7

-how genetic information is stored
-how genetic information is copied (and passed on to subsequent generations)

Question 8

what is a nucleotide made out of?

Answer 8

Question 9

what is the difference between a nucleotide and a nucleoside?

Answer 9

nucleotide
-deoxyribose sugar + base + phosphate group
-tide=tri (3 things)

nucleoside
-deoxyribose sugar + nitrogenous base
-doesn’t have a phosphate group

Question 10

what does a DNA strand look like as building blocks?

Answer 10

Question 11

what are the nitrogenous bases?

Answer 11

Question 12

what is Chargaff’s rule?

Answer 12

complimentary base-pairing

Question 13

what did rosalind franklin do?

Answer 13

used X-ray crystallography to discover the structure of DNA

Question 14

what were the first two things in the watson-crick proposal?

Answer 14

1. DNA is composed of two chains of nucleotides
2. the two chains antiparallel, they run in opposite directions

Question 15

what is the meaning of 5’ and 3’?

Answer 15

2. the two chains are antiparallel, they run in opposite directions

5’ and 3’ describe which carbon the phosphate group is attached to
-5’ end=phosphate group attached to carbon 5
-3’ end= phosphate group attached to carbon 3

Question 16

what were step 3 and 4 of the watson-crick proposal?

Answer 16

3. the sugar-phosphate backbone is the exterior of the molecule, and the bases are interior
4. bases are perpendicular to sugar-phosphate backbone (right angles)

Question 17

what is the fifth step of the watson-crick proposal?

Answer 17

5. the two chains form a spiral pair of right-hand helices

Question 18

what are steps 6-10 of watson-crick proposal?

Answer 18

6. DNA chains are held together by hydrogen bonds between bases
7. pyrimidines always paired with purines
8. double helix width 2nm
9. only A-T and C-G pairs fit within double helix (2nm)
10. complete turn is 10 base pairs

DNA strand with more C-G will be harder to break apart because more hydrogen bonds

Question 19

what is the 11 step of watson-crick proposal?

Answer 19

11. molecule has a major groove and a minor groove

Question 20

what is step 12 of watson-crick proposal?

Answer 20

12. complementary base sequences on each of the 2 strands (good explanation on how we can copy)

Question 21

what are all the aspects of watson-crick proposal?

Answer 21

1. DNA is composed of two chains of nucleotides
2. the two chains are antiparallel, they run in opposite directions
3. the sugar-phosphate backbone is the exterior of the molecule, and the bases are interior
4. bases are perpendicular to sugar-phosphate backbone
5. the two chains form a spiral pair of right-hand helices
6. DNA chains are held together by hydrogen bonds between bases
7. pyrimidines always paired with purines
8. double helix width is 2nm
9. only A-T and C-G pairs fit within double helix
10. complete turn is 10 base pairs
11. molecule has a major groove and a minor groove
12. complementary base sequences on each of the 2 strands

Question 22

the structure of DNA provides a mechanism for ____________

Answer 22

heredity

Question 23

what is the central dogma of molecular biology?

Answer 23

RNA can also be the final product

Question 24

in analyzing the number of different bases in a DNA sample, which result would be consistent with Chargaff’s findings?
a) A=G; G=T
b) A+G=C+T
c) A+T=G+T
d) A+C=G+C

Answer 24

b

Question 25

what is eukaryotic DNA packaged into?

Answer 25

eukaryotic DNA is packaged into multiple chromosomes -chromosome can be labeled with multicolored, fluorescent DNA probes that bind specifically to particular chromosomes karyotype: homologous chromosome pairs ordered according to size -pattern can be used to screen chromosomal abnormalities

Question 26

what do chromosomes do?

Answer 26

organize and carry genetic information

Question 27

what is the difference between a gene and a genome?

Answer 27

gene -segment of DNA that contains instructions to make a particular protein or RNA molecule genome -the entirety of an organism's DNA grey areas= DNA used for other things that aren't for protein coding

Question 28

what are the levels of chromosome organization?

Answer 28

1. chromosome=single, continuous DNA strand 2. nucleosome 3. chromatin fibers 4. looped domains

Question 29

what is the nucleosome?

Answer 29

-structural unit (of chromosome) -DNA+histones

Question 30

what is one of the most important functions of chromosomes?

Answer 30

protein synthesis -most genes contain information to make proteins

Question 31

what are other important functions of chromosomes?

Answer 31

specialized DNA sequences required for DNA replication and chromosome segregation

Question 32

what is important in specialized DNA sequences?

Answer 32

replication origin -site where DNA replication begins (what transcription machinery recognizes) (replication) telomere: repeated nucleotide sequences at end (replication) -replication of end of chromosome -protective cap (ensures accurate replication and protects DNA from degradation) centromere (segregation) -role in separation of duplicated chromosomes

Question 33

the behavior of what cell constituent correlated perfectly with that of Mendel's genetic factors: a) nucleolus b) the endoplasmic reticulum c) the homologous pairs of chromosomes d) the homologous pairs of centrioles

Answer 33

c

Question 34

during cell division, the nuclear material is organized into visible "threads" called ______ a) chromatids b) mitochondria c) chromophores d) chromosomes

Answer 34

d