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Bio 1 > Exam 4 > Flashcards

Exam 4 Flashcards

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Biology 101 flashcards
1
Q

Cell Division

A

The basis of reproduction, growth, and regeneration/repair

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2
Q

Four Division Events in Organisms

A
  1. Cell Division Signals
  2. DNA Replication
  3. DNA Segregation
  4. Cytokinesis
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3
Q

Binary Fission

A

The way in which prokaryotes divide

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4
Q

What are the signals for prokaryotes to divide by binary fission

A

Signals to divide are usually external factors such as environmental conditions and nutrient concentration

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5
Q

Does cell division always occur in eukaryotes if internal/environmental conditions are suitable for cell division?

A

No; commitment to divide depends on integration of extracellular and intracellular information

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6
Q

Steps of the Cell Cycle

A

G1, Interphase, G2, Mitosis (M phase)

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7
Q

In which phase of the cell cycle do eukaryotic cells divide

A

Eukaryotic cells only divide in the M phase of the cell cycle

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8
Q

Cycline-Dependent Kinases (CDKs)

A

Controls progress through the cell cycle; when activated, Cdk phosphorylates targets; when phosphorylated, these targets cause DNA replication enzymes to activate which makes S phase begin

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9
Q

Cdks are inactive without specific

A

Cyclines; each CDK is activated by binding to a specific cycline through allosteric regulation

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10
Q

What is each phase of the cell cycle characterized by

A

The activity of specific combinations of cyclin/Cdk

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11
Q

Restriction Point (R)

A

A control point in the cell cycle; progress past the restriction point depends on the phosphorylation of retinoblastoma protein (RB) by CDK4

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12
Q

Cell Cycle Checkpoints

A

Regulates progress through the cell cycle through cyclin-CDKs

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13
Q

Pass M checkpoints if

A
  • DNA has attached to spindle
  • DNA has been properly separated
  • Mitotic cyclin is absent
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14
Q

Pass G1 checkpoints if

A
  • Cell size is adequate
  • Nutrients are sufficient
  • Social signals are present
  • DNA is undamaged
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15
Q

Pass G2 checkpoint if

A
  • DNA is replicated successfully
  • DNA is undamaged
  • Activated mitotic cyclin is present
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16
Q

What is a key to regulating cell division

A

Since progress through the cell cycle depends on CDKs, regulating CDKs is a key to regulating cell division

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17
Q

Where is the genome stored

A

In chromosomes

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18
Q

Ori

A

Site of DNA replication in prokaryotes

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19
Q

How many chromosomes do prokaryotes have

A

One circular chromosome

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20
Q

How do prokaryotes replicated their DNA

A

Through theta replication

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21
Q

How many chromosomes do humans have

A

46 linear chromosomes

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22
Q

True or false: eukaryotic DNA replication has multiple origins

A

True

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23
Q

Sister Chromatids

A

Result of DNA replication; two identical copies of cell’s genetic material; they’re identical to one another in sequence and they’re physically attached

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24
Q

Chromatids vs chromosomes

A

Chromatids share a centromere, chromosomes have their own

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25
Q

When does eukaryotic DNA replication occur

A

S phase of the cell cycle

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26
Q

Cohesin

A

Protein complex that holds together sister chromatids; in G2, sister chromatids are held together along their length by cohesin

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27
Q

When is cohesin removed (except at centromere)

A

In prophase cohesin is removed except at the centromere, where the chromatids are held together

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28
Q

Mitosis

A

Allocates chromosomes into two new genetically identical nuclei in eukaryotes

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29
Q

Mitotic Spindle Apparatus

A

Consists of microtubules, moves DNA by binding to the kinetochore at the centromere of each sister chromatid

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30
Q

Kinetochore

A

A complex of proteins attached to the centromere

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31
Q

What is the orientation of the spindle and the direction DNA moves in determined by

A

The centrosome

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32
Q

What is the centrosome made up of

A

Two centrioles, which are mostly made of tubulin

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33
Q

Prophase/prometaphase of mitosis

A

Nuclear envelope is broken down and spindle is assembled

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34
Q

Metaphase of mitosis

A

Chromosomes line up at the metaphase plate

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35
Q

Anaphase of mitosis

A

First, the cohesin that holds sister chromatids together is removed by separase, allowing the sister chromatids to separate; then, daughter chromsomes are pulled to opposite poles of the cell

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36
Q

What is separase controlled by

A

The M phase Cdk-cyclin

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37
Q

What are sister chromatids called after they’re separated

A

Daughter chromosomes

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38
Q

Telophase of mitosis

A

The spindle dissolves, DNA decondenses, and the nuclear envelope re-forms

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39
Q

Cytokinesis in mitosis (animal cells)

A

Actin-myosin interactions pull plasma membrane inward to split the cell in two

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40
Q

Somatic Cells

A

Cells of the body; they’re made from mitosis

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41
Q

Diploid Cells

A

Cells that have two version of each chromosomes; they can have up to two versions of the same gene (alleles)

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42
Q

Alleles

A

A specific sequences of genes; versions of a gene

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43
Q

Heterozygous Cell

A

Has two different alleles of the same gene

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44
Q

Heterozygous Cell

A

Has the same allele of the same gene

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45
Q

Homologous Chromosomes

A

Chromosomes that share the same features but may contain different alleles

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46
Q

How many homologous pairs of chromosomes do humans have

A

22

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47
Q

Gametes

A

Egg and sperm cells; they only have one copy of each chromosome; haploid

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48
Q

Haploid Cells

A

Only have one copy of each chromosome

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49
Q

What yields a diploid cell

A

Union of haploid gametes at fertilization

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50
Q

Meiosis

A

How we make 4 haploid gametes from diploid cells; two nuclear divisions lead to the formation of haploid gametes that are genetically distinct

51
Q

Starting point of both mitosis and meiosis 1

A

Duplicated chromosomes from S phase

52
Q

Meiosis 1

A

Homologous chromosomes separate

53
Q

Prophase 1 of Meiosis

A

Homologous chromosomes pair up along their lengths (synapse) so they can align together in metaphase 1 (creates nonsister chromatids)

54
Q

Chiasmata

A

Regions of attachment that form between nonsister chromatids

55
Q

True or false: nonsister chromatids may have different alleles

A

True

56
Q

In heterozygous individuals, do nonsister chromatids have identical alleles?

A

No

57
Q

Crossing Over

A

Allowed by synapsis; contributes to genetically diverse products in meiosis; results in recombinant chromatids that aren’t found in parents

58
Q

What does meiosis 1 being a reductive division mean

A

One diploid parent cell becomes two haploid cells in meiosis 1

59
Q

Meiosis 2

A

Sister chromatids separate; phases are like mitosis but with recombinant chromatids

60
Q

Blending Inheritance

A

One of the two hypotheses for inheritance that emerged; in 1800s people thought that inheritance involved blending of parental traits; all future off spring would be the result of that blend

61
Q

Particulate Inheritance

A

One of the two hypotheses for inheritance that emerged; proved by Gregor Mendel in 1860s; showed genes don’t change from offspring

62
Q

Genotype

A

The combinations of alleles in a cell

63
Q

Phenotype

A

The physical manifestation of alleles in a cell

64
Q

Trait

A

Specific form of a characteristic (character: pea color, trait: yellow)

65
Q

What is the molecular basis of dominance

A

Many possible reasons; one is that genes determine phenotype through the proteins that they encode

66
Q

What yields a diploid cell

A

Union of haploid gametes at fertilization

67
Q

DNA makeup

A

Exactly 50% of our DNA is from our egg parent and 50% is from our sperm parent

68
Q

Monohybrid Cross

A

Two homozygous (true-breeding) parents with different traits are bred to produce all heterozygous F1s, which are crossed to each other

69
Q

When does segregation/separation of alleles occur

A

the two alleles of a gene in any diploid individual separate during meiosis; each gamete receives 1 allele of each gene

70
Q

Monohybrid cross F2 ratios

A

3:1 phenotypic ratio and 1:2:1 genotypic ratio (YY: Yy: yy)

71
Q

True or false: dominance of an allele does not mean that it is more fit or more common in population

A

True

72
Q

Mendel’s Law of Segregation

A

The two alleles of a gene in any diploid individual separate during meiosis; each gamete receives only allele of each gene

73
Q

Punnett Square

A

Used to predict genotypes and phenotypes in a cross

74
Q

Progeny

A

Offspring

75
Q

Dihybrid cross

A

Looks at 2 genes with differing traits at same time

76
Q

Dihybrid cross phenotypic ratio

A

9:3:3:1 (Both dominant traits:one dominant trait:other dominant trait: both recessive traits)

77
Q

Mendel’s Law of Independent Assortment

A

Alleles of genes on different chromosomes don’t travel together during anaphase

78
Q

Pedigrees

A

Used by geneticists to infer genotypes

79
Q

True or false: for rare dominant traits, every affected person has an affected parent

A

True

80
Q

True or false: for recessive traits, an affected individual may have unaffected parents

A

True

81
Q

How do mutations arise

A

Through mistakes in DNA replication/repair (insertion, subsitution, deletion)

82
Q

How do new alleles arise

A

Through mutations: stable, inherited changes in the genetic material

83
Q

Consanginous Mating

A

Mating between relatives

84
Q

Wild Type Allele

A

Most abundant allele in the population

85
Q

Mutant Allele

A

AKA variants; alleles that aren’t most abundant in the population

86
Q

True or false: Any one individual has two alleles at a locus, but there may be many alleles in the population

A

True

87
Q

True or false: multiple alleles often show a hierarchy of dominance

A

True

88
Q

Complete dominance

A

One of the types of dominance relationships; hybrid resembles one of the two parents

89
Q

Incomplete dominance

A

Alleles are neither dominant or recessive- heterozygotes have intermediate phenotypes

90
Q

Example of incomplete dominance

A

Purple and white fruit (p) makes heterozygote violet fruit (F1) and when those fruit breed, the original phenotypes reappear, along with violet heterozygotes (f2)

91
Q

Codominance

A

Alleles produce phenotypes that are both present in the heterozygote

92
Q

What defines the dominance in the relationship of two alleles

A

The phenotype of the heterozygote

93
Q

Phenylketonuria

A

Results from a mutation in the gene that encodes PAH, an enzyme thats required to convert phenylalanine to tyrosine

94
Q

Pleiotropy

A

When one allele has multiple phenotypic effects

95
Q

Discrete Traits

A

Aka qualitative traits; have definable forms (ex: color)

96
Q

Continuous Traits

A

Aka quantitative traits; have variable forms (ex: human height)

97
Q

Quantitative Trait Loci (QTL)

A

The chromosomal regions that together determine complex characters; can contain one or more genes

98
Q

Locus

A

A specific position on a chromosome

99
Q

What does identifying loci do

A

Helps to improve crop yields, and understand disease susceptibility and behavior

100
Q

How does environment affect phenotype

A

Light, temperature, nutrition, etc can affect expression of the genotype

101
Q

True or false: Genes produce a phenotype through the proteins they encode

A

True

102
Q

Melanocyte

A

Some of the genes that control coat color encode proteins that function in pigment-producing skin cells called melanocytes

103
Q

Epistasis

A

In epistasis, the phenotypic expression of one gene is influenced by another gene; it occurs when one gene alters the phenotypic effect of another gene

104
Q

Important F2 ratio (2 genes, recessive epistasis)

A

9:3:4 (dom:het:rec)

105
Q

Dioecious

A

Only produces male/female gametes (most animals are dioecious)

106
Q

In mammals and birds, what determines which gamete is produced

A

Sex chromosomes

107
Q

Autosome

A

Chromosomes that aren’t sex chromosomes

108
Q

SRY

A

A gene on the Y chromosome that determines male-ness

109
Q

Sex-linked traits like colorblindness are caused by a mutation on which chromsomes

A

X chromosomes

110
Q

Pedigrees of x-linked recessive traits

A
  • Phenotype appears more often in males
  • Heterozygous daughters are carriers
  • A male with the mutation can only pass it to his daughters
  • Mutant phenotype can skip a generation if it passes from a male to his daughter
111
Q

Thomas Hunt

A

Demonstrated that genes are present on chromosomes (~1915)

112
Q

Translocation

A

Occurs when a piece of one chromosome is moved onto another chromosome

113
Q

What causes shuffling of alleles of genes on the same chromosome

A

Crossing over during meiosis 1 causes shuffling of alleles of genes on the same chromosome that is obvious in a heterozygote

114
Q

How do recombinant genotypes form

A

When homologous chromosomes line up in metaphase 1, crossing over occurs as a result of homologous recombination

115
Q

Recombination does not occur often between

A

Linked genes

116
Q

How do we calculate the genetic distance between two genes

A

By calculating the frequency in which they recombine

117
Q

Recombination Frequency (RF) Formula

A

RF = number of recombinants/total number of offspring

118
Q

Relationship between closeness of genes and frequency of genes

A

The closer two genes are on the chromosome, the frequency that they will recombine is lower

119
Q

What do linked genes not obey

A

The law of independent assortment

120
Q

What is the maximum RF and what does it mean

A

50cM (50%); means genes are unlinked and will segregate independently

121
Q

Where do you get the data to calculate an RF

A

From a test cross

122
Q

Properties of linked genes

A

-Parentals>Recombinants (RF<50%)
- Linked genes must be syntenic and close together on the same chromosome so that they don’t assort independently

123
Q

Properties of unlinked genes

A
  • Parentals = recombinants (RF=50%)
  • Occurs either when two genes are on different chromosomes or when they are sufficiently far apart on the same chromosome that at least one crossover occurs between them in every meiosis
124
Q

Haplotype

A

A group of genes whose alleles are often inherited together; most commonly refers to a group of linked genes

Bio 1 (8 decks)

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