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Biology I > Ch.10 meiosis > Flashcards

Ch.10 meiosis Flashcards

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1
Q

Heredity

A

The transmission of traits from one generation to the next

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2
Q

Varations

A

Variation is demonstrated by the differences in appearance that offspring show from parents and siblings

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3
Q

Genetics

A

Is the scientific study of heredity and variation

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4
Q

Genes

A

Genes are the units of heredity and are made up of segments of DNA

In a literal sense, children do not inherit particular physical traits from their parents

Children inherit Genes from parents

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5
Q

Gamates

A

Genes are passed to the next generation via reproductive cells called gametes (sperm and egg/ova)

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6
Q

Asexual reproduction

A

A single individuall passes genes to its offspring without the fusion of gametes

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7
Q

Clone

A

is a group of gentically identical individuals from the same parent

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8
Q

sexual reproduction

A

two parents give rise to offspring that have unique combinations of genes from the two parents

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9
Q

Life cycle

A

the generation-to-generation sequence of stages in the reproductive history of
an organism

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10
Q

How many pairs of chromosomes do human somatic cells have?

A

23 pairs

total of 46 chomosomes diploid

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11
Q

karyotype

A

is an ordered display of the pairs of chromosomes from the cell

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12
Q

Homologous chromosomes (homologs)

A

The two chromosomes in each pair are called homologous chromosomes, or homologs

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13
Q

homologous pair

A

Chromosomes in a homologous pair are the same length and shape and carry genes controlling the same inherited characters

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14
Q

Sex chromosomes, what kind do males have and what kind do females have

What are autosomes

A

The sex chromosomes, which determine the sex of the individual, are called X and Y

Human females have a homologous pair of X chromosomes (XX)

Human males have one X and one Y chromosome

The remaining 22 pairs of chromosomes are called autosomes

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15
Q

Diploid cell

A

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 from the mother and one from the father

A diploid cell (2n) has two sets of chromosomes

For humans, the diploid number is 46 (2n = 46)

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16
Q

Haploid (n)

A

A gamete (sperm or egg) contains a single set of chromosomes and is haploid (n)

For humans, the haploid number is 23 (n = 23)

Each set of 23 consists of 22 autosomes and a single sex chromosome

In an unfertilized egg (ovum), the sex chromosome
is X

In a sperm cell, the sex chromosome may be either X or Y

17
Q

Fertilization and Zygote

A

fertilization is the union of gametes (the sperm and egg)

The fertilized egg is called Zygote and has one set of chromosomes from each parent

The Zygote produces somatic cells by mitosis and develops into an adult

18
Q

When are haploid gametes produced?

what process produces this?

A

At sexual maturity, the ovaries and testes produce haploid gametes

Gametes are the only types of human cells produced by meiosis rather than mitosis

Meiosis results in one set of chromosomes in each gamete

Fertilization and meiosis alternate in sexual life cycles to maintain chromosome number

19
Q

Alternation of generations

A

Plants and some algae exhibit an alternation of generations

This life cycle includes both a diploid and haploid multicellular stage

The diploid organism, called the sporophyte, makes haploid spores by meiosis

20
Q

fungi and reproduction

A

In most fungi and some protists, the only diploid stage is the single-celled zygote; there is no multicellular diploid stage

The zygote produces haploid cells by meiosis

Each haploid cell grows by mitosis into a haploid multicellular organism

The haploid adult produces gametes by mitosis

21
Q

meiosis I and meiosis II

A

Like mitosis, meiosis is preceded by the duplication
of chromosomes

Meiosis takes place in two sets of cell divisions, called meiosis I and meiosis II

he two cell divisions result in four daughter cells, rather than the two daughter cells in mitosis

Each daughter cell has only half as many chromosomes as the parent cell

22
Q

Meiosis and stages of division

A

Meiosis halves the total number of chromosomes very specifically

It reduces the number of sets from two to one, with each daughter cell receiving one set of chromosomes

In the first meiotic division, homologous pairs of chromosomes pair and separate

In the second meiotic division, sister chromatids of each chromosome separate

Four new haploid cells are produced as a result

23
Q

Meiosis prophase I

A

Chromosomes condense progresively throught prophase I

Homologous chromosomes pairs up, aligned gene by gene

24
Q

Cross over

A

non sister chromatides exchange DNA segments

Each homologous pair has one or more X-shaped regions called chiasmata

Chiasmata exist at points where crossing over has occurred.

25
Q

Metaphase I

A

In metaphase I, homologous pairs line up at the metaphase plate, with one chromosome facing each pole

Microtubules from one pole are attached to the kinetochore of one chromosome of each tetrad

Microtubules from the other pole are attached to the kinetochore of the other chromosome

26
Q

Anaphase I

A

Anaphase I

In anaphase I, pairs of homologous chromosomes separate

One chromosome moves toward each pole, guided by the spindle apparatus

Sister chromatids remain attached at the centromere and move as one unit toward the pole

27
Q

Telophase I and Cytokinesis

A

Telophase I and Cytokinesis

In the beginning of telophase I, each half of the cell has a haploid set of chromosomes

Each chromosome still consists of two sister chromatids

Cytokinesis usually occurs simultaneously, forming two haploid daughter cells

28
Q

Four Phases of meiosis II

A

Division in meiosis II also occurs in four phases

Prophase II

Metaphase II

Anaphase II

Telophase II and cytokinesis

Meiosis II is very similar to mitosis

29
Q

Prohphase II

A

Prophase II

§In prophase II, a spindle apparatus forms

§In late prophase II, chromosomes (each still composed of two chromatids) move toward the metaphase plate

30
Q

Metaphase II

A

Metaphase II

§The sister chromatids are arranged at the metaphase plate

§Because of crossing over in meiosis I, the two sister chromatids of each chromosome are no longer genetically identical

§The kinetochores of sister chromatids attach to microtubules extending from opposite poles

31
Q

Anaphase II

A

Anaphase II

§In anaphase II, the sister chromatids separate

§The sister chromatids of each chromosome now move as two newly individual chromosomes toward opposite poles

32
Q

Telophase II and Cytokinesis

A

Telophase II and Cytokinesis

§Nuclei form, and the chromosomes begin decondensing

§At the end of meiosis, there are four daughter cells, each with a haploid set of unduplicated chromosomes

§Each daughter cell is genetically distinct from the others and from the parent cell

Biology I (8 decks)

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