BIOL 1090 Lecture Notes - Lecture 3: Umber, Gametogenesis, Meiosis

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18 Jan 2018

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The process by which the umber of chromosomes in the reproductive cell is reduced from the diploid number (2n) to half this number (n) Occurs in vegetative (somatic) cells. (all cells beside germ cells) End up with 2 diploid, generally identical cells (2n, 2c: meiosis. End up with 4 haploid, genetically distinct cells (n,c) Prophase i: leptonema, zygonema, pachynema, diplonema, diakensis. Prophase i: leptonema: chromosomes, each consisting of two sister chromatids, begin to condense, zygonema: homologous chromosomes begin to pair. This is called synapsis and is often facilitated by formation of a synaptonemal complex: pachynema: homologous chromosomes are fully paired. Crossing over involves breakage of chromatids and the exchange of the broken pieces between homologous chromosomes. Crossover junctions are called chiasmata: diakinesis: paired chromosomes condense further and become attached to spindle. Metaphase i: paired chromosomes alight on the equatorial plane in the cell. Anaphase i: homologous chromosomes disjoin and move to opposite poles of the cell.

Related Questions

What is the purpose of meiosis?

To enable an organism to produce gametes

To allow for growth

To allow an organism to replace damaged cells

Question 2

Select one answer.

10 points

Mitosis results in ________ and meiosis results in ________.

gametes, somatic cells

gametes, gametes

somatic cells, somatic cells

somatic cells, gametes

Question 3

Select one answer.

10 points

Which of the following tasks is accomplished through the processof meiosis?

Cell growth

Production of sperm or eggs

Replacement of dysfunctional cells

Question 4

Select one answer.

10 points

What advantage does sexual reproduction have over asexualreproduction?

All other selections are true.

Sexual reproduction provides more genetic variability

Sexual reproduction doubles the number of chromosomes in aspecies

Sexual reproduction is more efficient

Question 5

Select one answer.

10 points

Crossing over occurs between homologous chromosomes during whatstage of cell division? (Read each option carefully.)

Prophase I of meiosis

Prophase of mitosis

Prophase II of meiosis

Interphase

Question 6

Select one answer.

10 points

Corn has 20 chromosomes. When corn undergoes meiosis how manychromosomes are found in the gametes?

Question 7

Select one answer.

10 points

Homologous chromosomes separate and are pulled to opposite sidesof the cell during what stage of cell division? (Read each optioncarefully.)

Metaphase I of meiosis

Anaphase II of meiosis

Anaphase I of meiosis

Anaphase of mitosis

Question 8

Select one answer.

10 points

Mitosis results in ______ cells and meiosis results in _______cells.

diploid, haploid

haploid, diploid

diploid, diploid

haploid, haploid

jadepug655

M2A1 Worksheet: Mitosis and Meiosis

A dog is a diploid organisms and has 39 pairs of chromosomes (2n = 78), where n = 39 chromosomes from each parent. Use this example to answer the following question regarding chromosomal number.

INTERPHASE

How many chromosomes are present in the somatic cell?

What do they look like?

What are they âdoingâ in G1 of this phase?

What is happening in the S phase?

What is happening in the G2 phase?

What follows G2 phase in a somatic cell?

What follows G2 phase in a gamete cell?

MITOSIS

Number of chromosomes in the parent cell.

Number of chromatids in the parent cell.

Number of chromosomes in the daughter cell.

Number of chromatids in the daughter cell.

How many daughter cells are produced?

Are the daughter cells haploid or diploid?

How many cell divisions take place?

In what type of cell does this division occur?

Meiosis 1:

Number of chromosomes in the parent cell.

Number of chromatids in the parent cell.

Number of chromosomes in each Meiosis I daughter cell.

Number of chromatids in each Meiosis I daughter cell.

Are the daughter cells haploid or diploid at the end of Meiosis 1?

Meiosis II:

Number of chromosomes in the âparentâ cell (which is a daughter cell from Meiosis I).

Number of chromatids in the âparentâ cell.

Number of chromosomes in each Meiosis II daughter cell.

Number of chromatids in each Meiosis II daughter cell.

Are the daughter cells haploid or diploid at the end of Meiosis II?

Which phase or phases of Meiosis account for the genetic variability among the daughter cells? Howâ¦ what happens in this phase to create the diversity?

Comparing Mitosis and Meiosisâ¦..

How many daughter cells result from Mitosis? Are they diploid or haploid?

How many daughter cells result from Meiosis? Are they diploid or Haploid?

Cell structures and function: Match each organelle to its function:

Organelle Function

Lysosome 1. Lipid synthesis

Rough ER 2. Houses DNA

Nucleus 3. Energy extraction

Smooth ER 4. Dismantles debris

Golgi apparatus 5. detoxification

Mitochondria 6. Protein synthesis

Peroxisome 7. Processes secretions

What is the function of checkpoint proteins in the cell cycle?

How can all of a personâs cells contain exactly the same genetic material, yet specialize as bone cells, nerve cells, muscle cells and connective tissues?

What are the 3 primary germ layers?

Briefly, in one or two sentences, distinguish between

a bacterial cell and a eukaryotic cell

interphase and mitosis

mitosis and apoptosis

an autosome and a sex chromosome

homologous pair of chromosomes and a sister chromatid

centromere and centriole

chromosome and chromatid

monozygotic and dizygotic twins

allele and gene

Consider each of the following statements.

In meiosis, the chromosomal material doubles during the lastpremeiotic interphase.

The greater the number of chromosome pairs, the greater is theeffect of meiosis in producing genetically distinct gametes.

The diploid number of chromosomes is half the haploidnumber.

A cell that will not divide again remains in the GÂ2 stage ofinterphase.

The correct sequence of events during meiosis is: synapsis ?dyad formation ? chiasma formation

In an organism with n = 3, there is a 1 in 8 probability of agamete with all maternally derived chromosomes contributing to theproduction of a zygote.

An organism with n = 3 can produce 8 different kinds of gametesin relation to combinations of maternal and paternalchromosomes.

Separation of sister chromatids occurs during anaphase I ofmeiosis and is the physical basis for the law of independentassortment.

A single diploid cell that undergoes meiosis in the male testiswill produce 4 genetically different gametes if crossing-over isignored.

The independent alignment of different tetrads at metaphase I ofmeiosis is the physical basis of the law of independentassortment.

If a diploid cell has 20 pairs of chromosomes, there will be 10tetrads during prophase I of meiosis.

If a diploid cell has 20 pairs of chromosomes, there will be 20bivalents during prophase I of meiosis.

If a diploid cell has 20 pairs of chromosomes, there will be 80chromatids present during metaphase of mitosis.

If a diploid cell has 20 pairs of chromosmes, the organism canmake 20² types of gametes if crossing-over isignored.

Segregation of sister chromatids occurs during anaphase I ofmeiosis and is the physical basis of the law of segregation.

For an individual with a diploid number of 30 chromosomes, therewill be 60 chromatids at metaphase I of meiosis.

For an individual with a diploid number of 30 chromosomes, therewill be 15 tetrads at metaphase II of meiosis.

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BIOL 1090 Lecture Notes - Lecture 3: Umber, Gametogenesis, Meiosis

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