BIOL 1221 Lecture Notes - Lecture 7: Gametogenesis, Meiosis, Dna Replication

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salmonswan911

16 Apr 2016

School

Mount Royal University

Department

Biology

Course

BIOL 1221

Professor

Tjandra

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Document Summary

Gamete formation: meiosis i, meiosis ii, gamete formation. Difers from mitosis: most body cells have 46 chromosomes - diploid chromosomal number (2n) One maternal, one paternal homologous chromosomes: gametes have 23 chromosomes - haploid chromosomal number (n) Two consecutive cell divisions (meiosis i and ii); only one round. Only one member of homologous pair of dna replication: produces four daughter cells, functions of meiosis: Number of chromosomes halved (from 2n to n) Introduces genetic diversity: random alignment of homologous pairs in meiosis i variability of gametes, crossover variability of gametes, ~ no two gametes exactly alike, ~ all diferent from original mother cells. Reduction division of meiosis reduces chromosome number from 2n n. Prophase i events not in mitosis or meiosis ii: synapsis - homologous chromosomes pair forming tetrads of four chromatids, crossover (chiasmata) exchange of genetic material between male and female chromatid unique chromosomes.

Related Questions

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

1). Explain the significance of the fact that gametes contain half of the chromosome complement of somatic cells. Tell me something about variation, if you have a sibling (if you don't imagine you do) - how is your sibling's genetic make-up similar and/or different from yours? What about your mom and dad?

2). Explain the terms reductional division and equational division. What is reduced or kept equal? To which nuclear divisions do these terms refer?

3). What is the diploid number (2n = ?) of an organism if it has
a) 12 chromosomes at Anaphase of Mitosis?
b) 12 chromosomes at Anaphase I of Meiosis?
c) 12 chromosomes at Anaphase II of Meiosis?

4). Compare/contrast Metaphase I of Meiosis with Metaphase of Mitosis.

5). What are the two mechanisms of variation in Meiosis, and during which stage(s) does each occur?

6). Draw a diagram of a bivalent and label the following parts: centromere, sister chromatids, non-sister chromatids, homologous chromosomes, chiasma.

7). A diploid cell has 1 pair of acrocentric chromosomes (Chromosome 1) and 1 pair of submetacentric chromosomes (Chromosome 2).
Â· Gene X is on Chromosome 1. Gene Y is on the short arm of Chromosome 2 and Gene Z is on the long arm of Chromosome 2.
Â· The maternal chromosomes have the X, y, z alleles, whereas the paternal chromosomes have the x, Y, Z alleles.
Draw these chromosomes, labeling ALL alleles, as they might appear in Metaphase I of Meiosis.

In order to move from G1 to S-phaseâ¦

Select one:

a. Cyclin-Cdk must phosphorylate cytochrome c, thereby inactivating it.

b. Cyclin-Cdk must phosphorylate cytochrome c, thereby activating it.

c. Cyclin-Cdk must phosphorylate RB, thereby inactivating it.

d. Cyclin-Cdk must phosphorylate ADP to make enough ATP for all that DNA synthesis.

e. Cyclin-Cdk must phosphorylate RB, thereby activating it.

How is meiosis different than mitosis?

Select one:

a. Meiosis is found only in juvenile organisms while mitosis is found at all life stages.

b. Cytokinesis is skipped during meiosis but not during mitosis.

c. During anaphase II of meiosis chromosomes segregate randomly while in mitosis they do not.

d. Meiosis is uncontrolled while mitosis is rigorously controlled.

e. During metaphase I of meiosis homologous chromosomes pair up together and in mitosis they do not.

C.)

âCrossing overâ during meiosis leads toâ¦

Select one:

a. the exchange of DNA on a maternal chromosome for DNA on paternal chromosome.

b. free radical formation and DNA damage.

c. incomplete formation of chiasmata.

d. many mitotic errors and mutations.

e. transcription and translation.

âNon-disjunctionâ during meiosis leads toâ¦

Select one:

a. robust, mutation-proof gametes.

b. parthenogenic reproduction.

c. larger zygotes.

d. the wrong number of chromosomes in the daughter cells.

e. is important for generating heritable genetic variability.

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BIOL 1221 Lecture Notes - Lecture 7: Gametogenesis, Meiosis, Dna Replication

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