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bio 1 > Unit 2 (Test 1) > Flashcards

Unit 2 (Test 1) Flashcards

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Biology 101 flashcards
1
Q

what is a gene?

A

a unit containing the code for a protein molecule or one of its parts, or for functioning RNA molecules.

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2
Q

what is a chromosome?

A

a DNA molecule with a part of or all the genetic material of an organism.

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3
Q

what does haploid mean?

A

there is one copy of each chromosome

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4
Q

what does diploid mean?

A

there are 2 copies of each chromosome

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5
Q

how many chromatids are there per chromosome?

A

2

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6
Q

what is a karyotype?

A

the entire collection of chromosomes found in an organism

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7
Q

what does the N mean?

A

a duplicated chromosome (2 sister chromatids)

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8
Q

how are chromosomes during G1?

A

unreplicated, 2 pairs of each chromosomes (2n)

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9
Q

how are chromosomes during G2?

A

each chromosome is doubled (2 sister chromatids) (2N)

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10
Q

how are the chromosomes during prophase?

A

they condense into threads that become visible under the microscope. They are still double (2N)

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11
Q

how are the chromosomes during prometaphase?

A

the microtubules attach to kinetichores of each chromosome. (2N)

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12
Q

how are the chromosomes during metaphase?

A

they align at the spindle midpoint (metaphase plate) (2N)

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13
Q

how are the chromosomes during anaphase?

A
  • now 92 chromosomes
  • now 4n : 4 unreplicated chromosomes
  • spindle separate the 2 sister chromatids and move them to opposite spindle poles creating daughter chromosomes
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14
Q

how are chromosomes during telophase?

A

they unfold and return to interphase state (4n)

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15
Q

what is aneuploidy?

A

an abnormal number of chromosomes

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16
Q

what are the causes of aneuploidy?

A

misdivision and nondisjunction

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17
Q

what is misdivision?

A

misdivision produces, during the second meiotic division, two normal gametes, one gamete with an extra chromosome and one with a missing chromosome

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18
Q

what is nondisjunction?

A

during the first meiotic division, both chromosomes of one pair are delivered to the same pole of the spindle. It creates 2 gametes with an extra and 2 with a missing chromosome.

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19
Q

what is mitosis?

A

a process in which a cell replicates its chromosomes, segregate them, producing 2 identical nuclei in peparation for cell division. It creates another identical cell.

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20
Q

what is meiosis?

A

a process to create gametes (sex cells) - 1n

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21
Q

what phases are in interphase?

A

G1, G2, S-phase

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22
Q

what is G1?

A
  • unreplicated chromosomes
  • organelles grow
  • RNA and proteins are synthesized
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23
Q

what is S-phase?

A
  • DNA is replicated
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24
Q

in what form is DNA during interphase?

A

as chromatin: DNA wrapped around with histones

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25
Q

what is G2?

A

-chromosomes are now 2 sister chromatids held together by a centromere
- DNA is checked for mistakes
- centrioles (in centrosome) have doubled in pairs

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26
Q

what is prophase?

A
  • first phase of mitosis
  • centrosomes divided into 2 parts generating the spindle
  • chromosomes condense
  • nuclear membrane breaks
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27
Q

what is prometaphase?

A

-microtubules generated by spindles attach to kinetochores of each chromosome

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28
Q

what is metaphase?

A
  • chromosomes align on metaphase plate
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29
Q

what is anaphase?

A
  • spindle seperates the 2 sister chromatids of each chromosome and move them to opposite spindle poles
  • centromeres break
  • 4 unreplicated chromosomes
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30
Q

what is telophase?

A
  • chromosomes decondense, unfold, and return to interphase state
  • nucleus reforms (2)
  • cytoplasm begins to divide
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31
Q

what is cytokinesis?

A
  • cytoplasm cleaves and divides into 2 daughter cells
32
Q

what is the interphase of meiosis?

A

same as mitosis (2n - 2N)

33
Q

what happens during prophase I in meiosis?

A
  • 2N
  • chromosomes begin to condense (2 sister chromatids per chromosome)
  • synapsis: homologous chromosomes come together and pair (4 chromatids within 2 homologous chromosomes - tetrad)
  • recombination: chromatids of homologous chromosomes undergo recombination and exchange segments
34
Q

what ensures genetic diversity?

A
  • recombination
  • independant assortment of chromosomes
35
Q

what happens in prometaphase I of meiosis?

A

same as mitosis (2N)

36
Q

what happens in metaphase I?

A
  • 2N
  • homologous pairs of chromosomes align randomly on metaphase plate = independant assortment
37
Q

what happens in anaphase I?

A
  • 2N
  • seperation of 2 chromosomes of each homologous pair and move to opposite spindle
  • no break in centromeres
  • poles now contain the haplooid number of chromosomes
38
Q

what happens in telophase I?

A
  • chromosomes undergo little to no change (don’t decondense)
  • first spindle disassembles and 2 new ones are created
  • 1N (division of cell)
39
Q

what happens after telophase I?

A

prophase II

40
Q

what happens in prophase II?

A
  • 1N
  • chromosomes condense and a spindle forms
  • no prometaphase since there is no nuclear membrane
41
Q

what happens in metaphase II?

A
  • 1N
  • chromosomes align on metaphase plate
42
Q

what happens during anaphase II?

A
  • 2n
  • microtubules seperate chromatids of each chromosome and go to opposite poles (2n)
43
Q

what happens in telophase II?

A
  • chromosomes decondense
  • new nuclear envelope
  • 4 (1n) cells
44
Q

what are alleles?

A

different versions of the same genes

45
Q

what does heterozygote mean?

A

different alleles

46
Q

Explain the relationship between meiosis, the segregation of chromosomes, and the transmission of alleles from parent to offspring.

A

During prophase 1: recombination and exchange in segments between homologous chromosomes

During metaphase 1: homologous chromosomes align randomly on metaphase plate (maternal and paternal are randomly placed on a side of the metaphase plate (pole))
The way they line up determines how they segregate in the cell and how end up in daughter cells (some have more maternal, or more paternal, etc)

Since there are infinite possibilities of assortments, there are infinite possibilities of gametes

47
Q

what is the effect of genetic recombination on chromosomes?

A

genetic recombination causes bits of genetic info to be exchanged to create new combinations of DNA in each chromosome

48
Q

what are the functions of meiosis?

A
  • reproduction
  • creation of genetic diversity
49
Q

what is a genotype?

A

the genetic constitution (different alleles) of an organism
(ex: BB, bb)

50
Q

what is a phenotype?

A

the outward appearance of an organism
(ex: round, wrinkled)

51
Q

what is a trait?

A

a heritable variation in character, such as flower color or pea shape.

52
Q

what does homozygote mean?

A

an individual with 2 identical alleles if the same gene

53
Q

what does autosome mean?

A

non sexual chromosome

54
Q

what are the sexual chromosomes?

A

X and Y

55
Q

what is complete dominance?

A

the dominant allele completely masks the effect of the recessive

56
Q

what is true breeding?

A

when the parents that are crossed are both homozygous for a gene

57
Q

what does dihybrid mean?

A

double heterozygous individual (hybrid of 2 traits ex: RrYy)

58
Q

what is a dihybrid cross?

A

crossing the dihybrids created by the cross of the homozygous parents

59
Q

what is the ratio of a dihybrid cross F2?

A

9:3:3:1

60
Q

what happens during a dihybrid cross in complete dominance?

A

the alleles of the genes that govern the two traits segregate independantly during the formation of the gametes = independant assortment

61
Q

what does the P generation create?

A

a dihybrid: heterozygous for both traits

61
Q

when do new phenotypes appear?

A

in F2 of a dihybrid cross

62
Q

what are the ways to know the chances of getting something specific of a dihybrid cross in complete dominance?

A
  • sum rule: when Punnett square already done (add the ones in the squares that fit the description)
  • product rule: when square not done (one trait at a time, muliply the chances)
63
Q

what is the point of a testcross?

A

to determine the zygosity of the dominant individual (PP or Pp)

64
Q

what is a testcross?

A

to cross the individual for which we want to determine the zygosity with a recessive homozygote. If the result gives 100% of the dominant phenotype, the individual is PP.

65
Q

what are mendel’s laws?

A
  1. the adult plants carry a pair of alleles that govern the inheritance of each trait
  2. if an individual’s pair of genes consists of different alleles, one allele is dominant over the other recessive allele.
66
Q

what is incomplete dominance?

A

when the F1 generation presents 100% new phenotype which is a mix of the two parent phenotypes

67
Q

what is the ratio for incomplete dominance F2 (dihybrid cross)?

A

1:2:1

68
Q

what is codominance?

A

-when both phenotypes are expressed (not mixed)
-no new phenotype

69
Q

what are the bonds between amino acids?

A

Peptide bonds (between COOH and NH2)

70
Q

what is a kinetichore?

A

special protein that holds centromeres to microtubules

71
Q

what is a centromere?

A

holds sister chromatids together

72
Q

what is the backbone of DNA?

A

deoxyribose and phosphate groups

73
Q

which cells are diploid in our body?

A

every cell except sex cells

74
Q

what does monogenetic mean?

A

that the traits are controlled by a single gene

75
Q

what is the ratio of F2 in monohybrid crosses?

A

3:1

bio 1 (5 decks)

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