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BI157 > Chapter 13 > Flashcards

Chapter 13 Flashcards

1
Q

What is hereditary?

A

transmission of traits from one generation to another

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2
Q

What is variation? (2)

A

reason identical copies from parents result in differences in offspring

the pheneotype

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3
Q

What are genetics? (2)

A

the scientific study of heredity and hereditary variation

the genotype

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4
Q

What are genes? (2)

A

hereditary units containing information/DNA

Programs cells to synthesize certain enzymes or proteins

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5
Q

What are gametes? (3)

A

reproductive cells that transmit genes

male gametes- sperm

female gametes- eggs

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6
Q

What is the locus?

A

gene’s specific location on a chromosome

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7
Q

What is asexual reproduction?

A

a single individual passes its genes without fusion of gametes

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8
Q

What is an example of asexual reproduction, and what does it result in?

A

Mitotic cell division

results with a clone (genetically identical individual)

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9
Q

What is sexual reproduction? (2)

A

two parents give rise to offspring with unique combinations of genes two parents

Vary genetically from siblings and parents

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10
Q

What is a life cycle?

A

sequence of stages in the reproductive history of an organism

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11
Q

What us a karyotype? (2)

A

pairs of chromosomes arranged from the longest

The two sets of 23 types of chromosomes are put together

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12
Q

What are homologous chromosomes/ homologs? (2)

A

pair of chromosomes with the same length, centromere position, and staining pattern

both pairs carry the same genes

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13
Q

What are human female chromosomes?

A

homologs of X chromosomes

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14
Q

What are human male chromosomes?

A

XY chromosomes

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15
Q

What are sex chromosomes, and what do they determine?

A

Human X and Y chromosomes

determines offspring’s sex

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16
Q

What are autosomes

A

non-sex chromosomes

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17
Q

What are diploid cells? (2)

A

cell with two sets of chromosomes (2n=46)

n= number of chromosomes in a single set

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18
Q

What are haploid cells? (2)

A

cells with only one set of chromosomes

In humans, the haploid number is 23

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19
Q

What is the human life cycle? (3)

A

Begins with fertilization, When a haploid sperm fuses with a haploid egg and fuses their nucleus

Forms a zygote- Diploid fertilized egg

As humans develop into sexually mature adults, mitosis of the zygote and its offspring generate somatic cells

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20
Q

How do gametes develop and reproduce? (4)

A

Only cells that do not produce through mitosis

Develop from germ cells in gonads

It cannot undergo mitosis if it does, it would become diploid

Undergoes meiosis

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21
Q

How is significant about gamete meiosis? (3)

A

Reduces the number of sets of chromosomes from two to one in gametes

Prevents doubling of chromosomes

Only diploid cells undergo meiosis

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22
Q

How do sexual life cycles vary?

A

Different species have different timing of fertilization and meiosis in their life cycle

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23
Q

What are the three groups of sexual life cycles?

A

humans and most animals

alternation of generations

fungi, protists, and algae

24
Q

What is the sexual life cycle of humans and most animals? (2)

A

gametes are the only haploid cells

Do not undergo further cell division other than meiosis prior to fertilization

25
Q

What is alternation of generations? (2)

A

Exhibited by some algae and plants

includes both a diploid and haploid stage

26
Q

What occurs during the diploid stage in the alternation of generations? (5)

A

AKA sporophyte

Produces haploids through miosis called spores

Spores do not fuse, but divide mitotically,

generating a haploid stage called gametophyte

gametophyte gives rise to gametes by mitosis

27
Q

What occurs during the haploid stage in the alternation of generations?

A

During fertilization, it results in a fusion of two haploid cells into a diploid zygote

Zygote develops into next the next sporophyte generation

28
Q

What occurs in the sexual life cycle of fungi, protists, and some algae? (4)

A

After gametes fuse and form a diploid zygote, meiosis occurs without a diploid offspring developing -

Produces haploid cells instead of gametes

Haploid cells divide by mitosis and give
rise to a descendent

The Descendent undergoes further mitosis to produce the cells that develop into gametes

29
Q

What is meiosis? (3)

A

Consists of two consecutive cycles, Meiosis 1 and Meiosis 2

Results in four daughter cells, one chromatid each, with half the amount of chromosomes as the parents

begins with a pair of sister chromatids, one from each parent

30
Q

What occurs during Meiosis 1?

A

Reduction division (reduces the number of chromosomes)

31
Q

What occurs during Prophase 1 early stage? (6)

A

Centrosome moves

Spindle forms

The nuclear envelope breaks down

Chromosome condenses

Chromosomes pair with their homolog

cross over occurs

32
Q

What is cross-over?

A

DNA molecules of chromatids are broken and rejoined with each other

33
Q

What occurs during Prophase 1 middle stage?

A

Each pair has one or more x-shaped regions called chiasmata where crossover overs

34
Q

What occurs during Prophase 1 late stage? (2)

A

Microtubules from one pole attach to the kinetochores

Homologous pairs will move toward the metaphase plate

35
Q

What occurs during Metaphase 1? (2)

A

Pairs of chromosomes are now on the plate

Both chromatids are attached to kinetochore microtubules from one pole

36
Q

What occurs during Anaphase 1? (3)

A

Proteins cleave sister chromatid cohesions along chromatid arms to separate

Homologs move toward opposite poles

Sister chromatid cohesion persists, causing chromatids to move as a unit

37
Q

What occurs during Telophase 1? (3)

A

Each half of the cell has a complete haploid set of duplicated chromosomes

Composed of two sister chromatids

One or both chromatids include regions of non-sister chromatid DNA

38
Q

What occurs during cytokinesis?

A

Occurs simultaneously with telophase, forming haploid daughter cells

39
Q

What occurs during Meiosis 2?

A

Equational division- chromosomal number remains equal as haploid

40
Q

What occurs during Prophase 2? (3)

A

Spindle forms

each chromosome still consists of two chromatids

moves towards metaphase 2 plate

41
Q

What occurs during Metaphase 2? (3)

A

Chromosomes are positioned at the metaphase plate

Because of crossover, chromatids are genetically different

Kinetochores are attached to microtubules from opposite poles

42
Q

What occurs during Anaphase 2? (2)

A

Proteins breakdown the cohesion of sister chromatids

Chromatids move to opposite poles

43
Q

What occurs during Telophase 2? (2)

A

Nuclei forms

chromosomes decondenses

44
Q

What is the result of meiosis? (2)

A

One parent cell produces four daughter cells with a haploid set of chromosomes

All genetically distinct from parent and sibling cells

45
Q

What occurs during the first step of crossover? (3)

A

During interphase, duplicated chromatids are held by cohesins

Each homologous pairs are associated along their length

DNA molecules get broken at corresponding points

46
Q

What occurs during the second step of crossover? (3)

A

Synaptonemal complex forms
- Zipperlike protein complex
- Attaches homologs to each other

47
Q

What occurs during the third step of crossover? (3)

A

Synaptonemal complex fully forms

Homologs are in synapsis

DNA breaks join to corresponding breaks, crossing over

48
Q

What occurs during the fourth step of crossover? (3)

A

Synaptonemal complex disassembles

Remains attached at cohesion

Crossover locations show up as chiasmata

49
Q

What is unique to meiosis when compared to mitosis? (3)

A

Synopsis and cross over

Homologous pairs at metaphase

Separation of homologs

50
Q

How do the sister chromatids differ in mitosis and meiosis?

A

In mitosis, remain together until anaphase

In meiosis, remain together until anaphase 2

51
Q

Where does genetic variation arise during sexual reproduction? (3)

A

Independent assortment of chromosomes

Crossing over

Random fertilization

52
Q

What is the independent assortment of chromosomes? (3)

A

Random orientation of homologous pairs at metaphase during meiosis 1

50% chance a daughter cell will get maternal chromosomes

Independent assortment- maternal and paternal homologs sort independently from every other pair

53
Q

How does crossing over result in genetic variation? (3)

A

Produces recombinant chromosomes

Individual chromosomes carrying genes from different parents

About 1-3 crossovers occur per pair

54
Q

What is random fertilization?

A

The fusion of the male gamete and female gamete produces a zygote with trillions of diploid combination

55
Q

How does genetic variation and evolution correlate? (2)

A

The population evolves from the reproductive success of its variants

Sexual reproduction generated genetic diversity

BI157 (21 decks)

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