CH.13 Biology

Human gametes are produced by _____.

-Meiosis -Meiosis produces haploid gametes from a diploid parental cell.

Homologous chromosomes

-The two chromosomes in each pair are called. - pair are the same length and carry genes controlling the same inherited characters -2 chromosomes of a pair have the same length, centromere position, and staining pattern.

Imagine you found a hypothetical organism. You examine one of its gametes and you see that it contains 5 chromosomes. How many chromosomes will one of its body cells contain just before mitosis begins?

10 -If the hypothetical organism has 5 chromosomes in one of its gametes, then it must have 10 chromosomes in a body cell. Just before mitosis, the chromosomes in a body cell are duplicated, but the sister chromatids remain joined together. So you will see 10 (duplicated) chromosomes in a typical body cell.

A diploid organism whose somatic (nonsex) cells each contain 32 chromosomes produces gametes containing _____ chromosomes.

16

Normal human gametes carry _____ chromosomes. This is the number of chromosomes in a single set of human chromosomes.

23

Human gametes have ________________ number of chromosomes and human somatic cells have _______________ chromosomes.

46

Synapsis occurs during _____.

Prophase I -Synapsis, the pairing of homologous chromosomes, occurs during prophase I.

During _____ a spindle forms in a haploid cell.

Prophase II -Prophase II is essentially the same as mitotic prophase except that the cells are haploid.

Differentiate between Asexual reproduction and sexual reproduction.

Sexual: vary genetically from their siblings & both parents. Variations on a common theme of family resemblance, not exact replicas.

At the end of _____ and cytokinesis, haploid cells contain chromosomes that each consist of two sister chromatids.

Telophase I -At the end of telophase I and cytokinesis, there are two haploid cells with chromosomes that consist of two sister chromatids each.

Asexual reproduction

a single individual is the sole parent and passes copies of all of its genes so its offspring without the fusion of gametes. one parent produces genetically identical offspring by mitosis

Somatic cell

all cells of the body except the gametes and their precursors. Humans have 23 pairs of chromosomes.

Homologous chromosomes migrate to opposite poles during _____.

anaphase I -During anaphase I sister chromatids remain attached at their centromeres, and homologous chromosomes move to opposite poles.

What name is given to this process?A single individual is reproducing.

asexual reproduction

Here i am representing a duplicated chromosome. What structure is represented by my waist where I am joined to my twin?

centromere -The centromere is the point of attachment between two sister chromatids of a duplicated chromosome.

Meiosis II typically produces _____ cells, each of which is _____.

four... haploid -At the end of meiosis II there are typically 4 haploid cells.

Haploid

gametes contain a single set of chromosomes. -A gamete (sperm or egg) contains a single set of chromosomes -For Humans is 23 (n=23)

If you look through a microscope and see a cell with chromosomes lined up two by two, what stage of cellular reproduction must you be looking at?

meiosis I only -Meiosis I is the only time that chromosomes line up by homologous pairs.

During _____ chromosomes align single file along the equator of a haploid cell.

metaphase II -Metaphase II is essentially the same as mitotic metaphase except that the cell is haploid.

Of the two processes we learned about which is going on in my hand right now

mitosis -Mitosis goes on continuously in most parts of the body, whereas meiosis takes place only in the gonads.

At the end of _____ and cytokinesis there are four haploid cells.

telophase II -At the end of telophase II and cytokinesis there are four haploid cells.

Imagine I've taken a snapshot of the chromosomes in a hypothetical cell. Two chromosomes lined up. You and your twin and your friends and her twin. Part of that snapshot looks like this. What stage of the lifecycle must that cell be in?

the start of meiosis I -We can see that the chromosomes are duplicated and lined up by homologous pair. That only happens at the start of meiosis I.

Meiosis I produces _____ cells, each of which is _____.

two ... haploid -At the end of meiosis I there are two haploid cells.

Sexual reproduction

two parents give rise to offsprings that have unique combinations of genes inherited from the 2 parents.

How are sister chromatids and homologous chromosomes different from each other?

Homologous chromosomes contain the same gene loci but may have different alleles of a particular gene. Sister chromatids are identical copies of each other produced during DNA replication. -One homologous chromosome comes from the father, and the other comes from the mother. Sister chromatids are identical copies of each other.

Gamete

In animals/plants reproductive cells are the vehicles that transmit genes from one generation to the next. Genes are passed to the next generation through reproductive cells of (sperm and eggs)

During _____ sister chromatids separate.

Anaphase II -Anaphase II is essentially the same as mitotic anaphase except that the cell is haploid.

Diploid

Any cell with 2 chromosome set. has a number of chromosomes abbreviated 2n -humans diploid # is 46 (2n=46) the # of chromosomes in our somatic cell

Differentiate between Asexual reproduction and sexual reproduction.

Asexual: only organisms that reproduce asexually have offspring that are exact genetic copies of themselves. Ex: single celled eukaryotic organism can reproduce asexually by mitotic cell division, in which DNA is copied & allocated equally 2 daughter cells. Genomes are virtually exact copies of the parent's genomes.