Lecture 6: Chromosomes, Recombination, DNA

Question 1

chromosomes

Answer 1

-found within a cell nucleus made of DNA that contains genes

Question 2

how many chromosomes do humans have?

Answer 2

-46 chromosomes total, 23 from mom and dad

Question 3

karyotype

Answer 3

-a map of a set of chromosomes

Question 4

chromatid

Answer 4

-each half of a duplicated chromosome

Question 5

sister chromatids

Answer 5

-just before cell division the DNA material replicaes and 2 chromatids, each with identical information on them, are paired

Question 6

centromere

Answer 6

• holds sister chromatids together

- central part of the chromosome

Question 7

homologous pair

Answer 7

-when one chromosome from both parents form a doubled pair

Question 8

ploidy

Answer 8

-number of copies of chromosomes

Question 9

sex chromosomes

Answer 9

• one of the two chromosomes that determine an individual’s sex
• females have 2 X chromosomes; malse have one X and one Y chromosome

Question 10

crossing over

Answer 10

-the mutual exchange of segments of genetic material btwn non-sister chromatids of two homologous chromosomes so as to produce

Question 11

recombination

Answer 11

-process by which the combinations of alleles for different genes in two parental individuals become stuffed into new combinations in offsprings individuals

Question 12

how do chromosomes explain gene linkage?

Answer 12

• whether or not traits are linked determes what gamete combinations can be produced
• but this is also determined by how close genes are on a chromosome

Question 13

does recombination eliminate gene linkage?

Answer 13

-no because depending on the location of the genes on the chromosome determines which genes are more likely to be together

Question 14

the basic structure of DNA

Answer 14

-two intertwined helical strands of nucleotides held together by hydrogen bonds (aka double helix)

Question 15

nucleotides types

Answer 15

• adenine(A)=thymine(T)

- cytosine(C)=guanine(G)

Question 16

loosely linked genes

Answer 16

• futher apart distance of genes on a chromosome

- higher likelyhood that recombinatin will end up separating them

Question 17

how does DNA replicate?

Answer 17

-a single strand of parental DNA w two chains can give rise to two daughter strains that will contain the exact info as the parental strand, due to complimentary pairing

Question 18

what is the central dogma of molecular biology?

Answer 18

-portions of DNA (the genes) get converted into RNA which provide instructions to the cell for the production of protein

Question 19

what do comparisons of amino acid sequences (cytochrome C), gene functions, or DNA sequences tell us about organism relatedness?

Answer 19

• when you sequence the amino acids for a particular protein from a variety of organisms, you can look to see how the amino acids have changed to see how closely related they are
  
  • -> the most popular amino acid sequence to use to see that^ is cytochrome C
  • -> its in all living things and is small which make it useful in studies of evolutionary relatedness

Question 20

transcription

Answer 20

• process of copying DNA into RNA

- occurs inside nucleus

Question 21

translation

Answer 21

• process of turning RNA into protein

- occurs outside nucleus

Question 22

how are proteins formed?

Answer 22

• DNA–>RNA–>protein
• copies of the “instructions” (DNA) are made and the single stranded copies of the DNA are now RNA
• RNA leaves the nucleus to instruct other organelles to make the proteins, which then can go wherever they’re needed to do the work of the cell

Question 23

basics of mitosis

Answer 23

• DNA condenses and replicates, cytoskeleton disassembles, mitosis spindle forms, chromosomes align along spindle (1 copy each), sister chromosomes separate on ends of all and cell break in half
  
  • ->cells will be identical

Question 24

basics of meiosis

Answer 24

-DNA replicate and condense, meiotis spindle forms, homologous pairs form and join, crossing over occurs, 1 chromosome pulls apart and sister chromosomes stay together, chromosomes align again and divide, 4 cells result

Question 25

cell outcomes/differences

Answer 25

• mitosis: 2 cells result, all diploid, cells will be identical, chromosomes line up in single file
• meiosis: 4 gametes results, all haploid, cells won’t be identical, chromosomes line up in middle in homologous pairs