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Bio 1 > Chapter 13: Meiosis and Sexual Reproduction (Test 3) > Flashcards

Chapter 13: Meiosis and Sexual Reproduction (Test 3) Flashcards

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Biology 101 flashcards
1
Q

___ is the transmission of traits from one generation to the next

A

•Heredity

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2
Q

•Variation is demonstrated by ___ that offspring show from parents and siblings

A

the differences in appearance

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3
Q

•Genetics is ___

A

the scientific study of heredity and variation

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4
Q
  • In a literal sense, children do not inherit particular physical traits from their parents
  • It is ___ that are actually inherited
A

genes

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5
Q

•Genes are the ___, and are made up of ___. Genes are packaged on chromosomes.

A

units of heredity

segments of DNA

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6
Q

•The ___ is the entire set of genetic instructions within an organism.

A

genome

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7
Q

•Each gene has a specific location called a ___ on a certain chromosome

A

locus

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8
Q

•Genes are passed to the next generation through reproductive cells called ___ (sperm and eggs)

A

gametes

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9
Q

•After FERTILIZATION - fusion of a sperm cell and ovum (egg), genes from both parents are present in the nucleus of the fertilized egg, or ___.

A

ZYGOTE

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10
Q

•Every living species has a characteristic number of chromosomes. Humans have ___ in their somatic cells.

A

23 pairs (or 46) chromosomes

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11
Q

•In asexual reproduction, one parent produces genetically identical offspring by___

A

mitosis

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12
Q

•In ___, two parents give rise to offspring that have unique combinations of genes inherited from the two parents

A

sexual reproduction

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13
Q

•A ___ is the generation-to-generation sequence of stages in the reproductive history of an organism

A

life cycle

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14
Q

•A life cycle starts at ___ and continues until the organism ___.

A

conception of an organism

produces its own offspring

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15
Q

•Human ___ cells (any cell other than a gamete) have 23 pairs of chromosomes

A

somatic

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16
Q

•A ___ is an ordered display of the pairs of chromosomes from a cell

A

karyotype

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17
Q

•___, are pairs of chromosomes that are the same length and carry genes controlling the same inherited characters

A

Homologous chromosomes

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18
Q
  • Each human somatic cell has ___ of sex chromosomes.
  • Human females have a ___
  • Human males have ___
A

ONE pair

homologous pair of X chromosomes (XX)

one X and one Y chromosome (XY)

19
Q

•The other 22 pairs of homologous chromosomes that do not determine sex are called ___

A

autosomes

20
Q
  • Each pair of homologous chromosomes includes one chromosome from each parent
  • The 46 chromosomes in a human somatic cell are two sets of 23: one set from the mother and one set from the father
A

just review

21
Q
  • A ___ (2n) has two sets of chromosomes. Somatic cells are DIPLOID.
  • For humans, the diploid number is 46 (2n = 46)
A

diploid cell

22
Q
  • In a cell in which DNA synthesis has occurred, each chromosome is ___
  • Each replicated chromosome consists of two ___
A

replicated

identical sister chromatids

23
Q

•Sperm cells or ova (gametes) contains a single set of chromosomes, and is ___(n)

A

haploid

24
Q
  • Each set of 23 consists of ___
  • An unfertilized ovum contains ___
  • A sperm cell contains ___
A

22 autosomes and a single sex chromosome

22 autosomes and an X

22 autosomes and an X or Y

25
Q

•Fertilization is ___ (the sperm and egg).Each gamete is haploid (n)

A

the union of gametes

26
Q

•The fertilized egg is called a ___ and has one set of chromosomes from each parent. The zygote is ___(2n)

A

zygote

diploid

27
Q

•At sexual maturity, the ovaries and testes produce ___

A

haploid (n) gametes

28
Q
  • Gametes are the only types of human cells produced by ___, rather than mitosis
  • Meiosis results in ___ in each gamete (gametes are haploid)
A

meiosis

one set of chromosomes

29
Q

•Gametes fuse to form a ___ that divides by mitosis to develop into a multicellular organism

A

diploid zygote

30
Q

•Like mitosis, meiosis is preceded by ___

A

the replication of chromosomes

31
Q
  • Meiosis takes place in two sets of cell divisions, called ___
  • The two cell divisions result in ___, rather than the two daughter cells in mitosis
A

meiosis I and meiosis II

four daughter cells

32
Q

The Stages of Meiosis I

  • In the first cell division (meiosis I), ___ separate
  • This results in 2 haploid cells (each daughter cell only has one set of replicated chromosomes)
A

homologous chromosomes

33
Q

Animal cell division 1 of 2

A
34
Q

Animal cell division 2 of 2

A
35
Q

The stages of Meiosis II

  • In the second cell division (meiosis II), ___ separate
  • The two cell divisions result in ___,
  • Each daughter cell has ___ as the parent cell
A

sister chromatids

four daughter cells

only half as many chromosomes

36
Q

A comparion of Mitosis and Meiosis

  • Meiosis reduces the number of chromosomes sets from two (diploid) to one (haploid), producing cells that differ genetically from each other and from the parent cell
  • Mitosis conserves the number of chromosome sets, producing cells that are genetically identical to the parent cell
A

you remember?

37
Q

Three events are unique to meiosis I and these events result in VARIATION amongst gametes

– Synapsis and crossing (prophase I): Homologous chromosomes physically connect and exchange genetic information

– Alignment of homologous chromosomes (homologs) on the metaphase plate instead of individual replicated chromosomes as in mitosis

– Separation of homologous chromosomes at anaphase I instead of sister chromatids as in mitosis

A

remember?

38
Q

Genetic variation produced in sexual life cycles contributes to evolution

  • Mutations (changes in an organism’s DNA) are the original source of genetic diversity
  • Mutations create different versions of genes called ___
  • Reshuffling of alleles during sexual reproduction produces genetic variation
A

alleles

39
Q

Origins of Genetic Variation Among Offspring

  • The behavior of chromosomes during meiosis and fertilization is responsible for most of the variation that arises in each generation
  • Three mechanisms contribute to genetic variation:

–Independent assortment of chromosomes (metaphase I/anaphase I of meiosis)

–Crossing over (prophase I of meiosis)

–Random fertilization

A
40
Q

Independent Assortment of Chromosomes

  • Homologous pairs of chromosomes orient randomly at metaphase I of meiosis
  • In independent assortment, each pair of chromosomes sorts maternal and paternal homologues into daughter cells independently of the other pairs
A

remember?

41
Q
  • The number of combinations possible when chromosomes assort independently into gametes is 2n, where n is the ___
  • For humans (n = ___), there are more than 8 million (223) possible combinations of chromosomes
A

haploid number

23

42
Q

Crossing Over (Prophase I)

  • Crossing over produces ___, which combine genes inherited from each parent
  • In crossing over, homologous portions of two nonsister chromatids trade places at___
  • A “hybrid” chromosome is produced by combining two non-identical chromatids into a single chromosome (contains shuffled genetic info from maternal and paternal chromosomes)
A

recombinant chromosomes

synapsis

43
Q

Random Fertilization

  • Random fertilization adds to genetic variation because any sperm can fuse with any ovum (unfertilized egg)
  • The fusion of two gametes (each with 8 million possible chromosome combinations from independent assortment alone) produces a zygote with any of about 70 trillion diploid combinations!!!!!
A

remember?

44
Q
A

hopefully this makes sense to you lol

Bio 1 (34 decks)

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