Sexual Reproduction

Meiosis I: Anaphase I

Homologous pairs separate and move toward opposite poles of the cell

Which statement regarding the differences between mitosis and meiosis is false? - In meiosis four daughter cells are produced, whereas in mitosis two daughter cells are produced. - In mitosis, cytokinesis occurs once, whereas meiosis cytokinesis occurs twice. - Crossing over is a phenomenon that creates genetic diversity during mitosis.

- Crossing over is a phenomenon that creates genetic diversity during mitosis.

Meiosis I: Telophase I

- Duplicated chromosomes have reached the poles. - A nuclear envelope re-forms around chromosomes in some species. - Each nucleus has a haploid number of chromosomes.

Difference between mitosis and meiosis

- Meiosis has two rounds of genetic separation and cellular division while mitosis only has one of each. - In meiosis, homologous chromosomes separate leading to daughter cells that are not genetically identical. - In mitosis, the daughter cells are identical to the parent as well as to each other.

Which statement regarding the diploid life cycle is false? - Gametes are haploid cells. - Two haploid cells duse during fertilization. - Meiosis of the zygote generates somatic cells. - A zygote is a fertilized egg.

- Meiosis of the zygote generates somatic cells

Meiosis I: Prophase I

- The nuclear membrane dissolves. - Chromatin tightly coils up. Homologous chromosomes, each composed of two sister chromatids, come together in pairs in a process called synapsis. - During synapsis, chromatids of homologous chromosomes exchange segments in a process called crossing over. - The chromosome tetrads move toward the center of the cell.

With the exception of identical twins, siblings who have the same two biological parents are likely to look similar, but not identical, to each other because they have: - identical chromosomes but different genes - identical genes but different chromosomes - the same combination of traits but different genes - a similar but not identical combination of genes

- a similar but not identical combination of genes

Which is the correct order of events in meiosis? - sister chromatids are separated, chromosomes are duplicated, homologous pairs are duplicated, sister chromatids line up - homologous pairs are separated, sister chromatids are separated, sister chromatids line up, chromosomes condense - chromosomes are duplicated, sister chromatids are separated, homologous pairs are separated, homologous pairs line up - homologouse pairs line up next to each, sister chromatids are separated, chromosomes are duplicated - chromosomes are duplicated, homologous pairs line up next to each other, homologous pairs are separated, sister chromatids are separated

- chromosomes are duplicated, homologous pairs line up next to each other, homologous pairs are separated, sister chromatids are separated.

Which statement correctly describes the behavior of a tetrad during anaphase I of meiosis? - It travels intact to one pole of the dividing cell. - It splits into two pairs of sister chromatids, and one pair goes to each pole of the dividing cell. - It splits into two pairs of homologous, non-sister chromatids, and one pair goes to each pole of the dividing cell. - It splits into four chromosomes, which distribute in random pairs to the two poles of the dividing cell.

- it splits into two pairs of sister chromatids, and one pair goes to each pole of the dividing cell.

Which statement regarding sexual and asexual reproduction is true? - cell division only occurs after sexual reproduction. - only offspring from asexual reproduction inherit traits from two parents. - sexual reproduction typically includes the development of unfertilized eggs - sexual reproduction is more likely to increase genetic variation than is asexual reproduction.

- sexual reproduction is more likely to increase genetic variation than is asexual reproduction

Metaphase of meiosis I and meiosis II differ in that... - there are the same number of chromosomes - chromosomes line up at the equator of the cell - homologs line up in meiosis I and duplicated chromosomes line up in meiosis II - sister chromatids (homologous chromosomes) line up in meiosis I and chromosomes line up in meiosis II

- sister chromatids (homologouse chromosomes) line up in meiosis I and chromosomes line up in meiosis II

Meiosis

- the number of chromosomes is cut in half by separating each member of a homologous pair; thus no information is lost in the process. - turns diploid cells into haploid cells by separating homologous pairs. - Interphase w/ G1, S, and G2 to separate sister chromatids. - Goes through 2 rounds of division - meiosis I (separates homologous chromosomes) & meiosis II (separates sister chromatids)

Human sex cells (sperm and egg) contain only

1 set of 23 chromosomes and are designated "n" for haploid.

The haploid number of chromosomes for humans is

23

A haploid gorilla cell contains 24 chromosomes. How many chromosomes would a diploid gorilla contain?

24

A domestic dog's diploid number of chromosomes is

2n = 78

A fruit fly's diploid number of chromosomes is

2n = 8

Domestic cats have a total of 38 chromosomes in each somatic cell. The diploid number of chromosomes is _____ and the haploid number of chromosomes is _____.

38; 19

A domestic dog's haploid number of chromosomes is

39

Fruit fly's haploid number of chromosomes is

4

The diploid number of chromosomes for humans is

46 (2n = 46)

Human somatic cells have ______ chromosomes and _______ sets of chromsomes.

46; 2

Explain the difference between a diploid cell and a haploid cell.

A diploid cell contains 2 complete sets of chromosomes from each parent while a haploid cell has a single set of unpaired chromosomes.

Karyotype

A display of the chromosome pairs of a cell arranged by size and shape in the cell nucleus of an organism or species.

Asexual repoduction

A reproductive process that involves only one parent and produces offspring that are identical to the parent.

At which stage of meiosis do chromatids separate and become daughter chromosomes? - metaphase II - metaphase I - anaphase I - anaphase II - telophase II

Anaphase II

Which sexually reproducing species has characteristic haploid and diploid numbers of chromosomes?

Any

Variation

Any difference between individuals of the same species.

What is the role of the protein in genes

Each protein controls 1 trait. i.e blood type or eye color or ability to taste specific chemicals

HBB gene

Hemoglobin beta gene that is mutated to cause sickle cell anemia and is responsible for coding for hemoglobin.

Independent assortment

Independent segregation of genes during the formation of gametes

Crossing over is important because

It allows for more genetic diversity of gametes.

How is variation beneficial to evolution?

Meiosis (reduction division) takes diploid cells and creates haploids from them

Hemoglobin

Oxygen carrying pigment in red blood cells

What are the steps of meiosis?

Prophase 1, Metaphase 1, Anaphase 1, Telophase 1, Prophase 2, Metaphase 2, Anaphase 2, Telophase 2

During which phase of meiosis does the nuclear membrane reform around chromosomes?

Telophase II

Chiasmata

The X-shaped, microscopically visible region representing homologous chromatids that have exchanged genetic material through crossing over during meiosis.

Anaphase II

The centromere divides. The chromatids seperate and move to opposite ends of the cell. Each chromatid is now an individual chromosome.

Prophase II

The first phase of meiosis II. Prophase II is identical to mitotic prophase, except that the number of chromosomes was reduced by half during meiosis I.

Meiosis I : Metaphase I

The homologous chromosome pairs line up along the cell's equator (metaphase plate). Bivalents (homologous pairs) that come from the mother or the father line up randomly on either side of the cell equator, independently of the other homologous pairs. Each bivalent has a special protein structure called a kinetochore where spindle fibers attach during division to pull the chromosomes apart. These kinetochores are attached to spindle fibers that are attached to the opposite poles.

Meiosis I: Prometaphase I

The nuclear envelope completely breaks down as the mitotic spindle connects to kinetochores on chromosomes.

Sexual reproduction

The process by which cells from two different parents unite to produce the first cell of a new organism.

Genetics

The scientific study of heredity and heredity variation.

What does the sequence of genes determine?

The sequence tells a ribosome what order to put amino acids in to make a protein.

Telophase II

The spindle fibres disappear, and a nuclear membrane forms around each set of chromosomes.

Prometaphase II

The stage of meiosis II in which the meiotic spindles attach to kinetochores on chromosomes.

Gene

a stretch of DNA nucleotides in a specific sequence; a recipe to make a protein.

The 15th chromosome in humans carries a gene for the ______.

blood protein hemoglobin.

Karyotyping

can reveal alterations in chromosome number

Recombinant chromatids

chromatid containing genetic information from both parents as a result of crossing over

Metphase II

chromosomes line up in single file around the equator, stage of meiosis

Several genetic disorders can happen when passed to offspring through the inheritance of ______________.

chromsomes

Meiosis is the process of _______

gamete (sex cell) information.

Diploid (2n)

containing two complete sets of chromosomes, one from each parent.

During meiosis I, what happens?

crossing over, homologous chromosomes line up at the middle of the cell, and independent assortment

Alleles

different versions of the same gene

Are your liver cells haploid or diploid

diploid

Somatic cells are

diploid (2n).

Crossing over

exchange of genetic material between homologous chromosomes during prophase I of meiosis

Which of the following lists contains events and/or components used in sexual reproduction? - fertilization, homologous chromosomes, meiosis - meiosis, mitosis, asexual - diploid, karyotype, sex chromosomes - asexual, clones, haploid - autosomes, clones, diploid

fertilization, homologous chromosomes, meiosis

Fertilization

fuses 2 haploid cells together to form a new diploid organism; haploid cells can fertilize or fuse are sex cells or gametes

sexually reproducing organisms produce...

gametes (sperm and egg).

Chromosomes carry _______ on them which are expressed as traits in the organism.

genes

Are egg and sperm diploid or haploid?

haploid

Human body cells

have 46 chromosomes, but 23 different, unique chromosomes in a human body cell. 1 set of 23 from mother; another 23 set from father.

Haploid (n)

having a single set of unpaired chromosomes

Every chromosome, whether bacterial or eukaryotic, has

hundreds to thousands of genes.

All of the following are characteristics of crossing over except: - independent assortment - homologous chromosomes line up next to each other - different combinations of alleles are formed - genetic diversity is increased - homologous chromosomes exchange parts of chromosomes

independent assortment

Both mitosis and meiosis follow after

interphase.

Sister chromatids are

joined together at a centromere

What are homologous chromosomes?

matched pairs of chromosomes in a diploid organism; also, it has the same length and has the same genes in the same location-- however, each copy of the homologous pair comes from a different parent thus a version of the gene may be different and not identical. i.e blood type A and blood type B; brown vs green eyes

Homologous chromosomes move towards opposite poles of the dividing cell during

meiosis I

When during meiosis do homologous chromosomes separate?

meiosis I - first division

When during meiosis do sister chromatids separate?

meiosis II - second division

What is the stage of cell division in a diploid organism if you see seven chromosomes, each consisting of a pair of sister chromatids?

meiosis II prophase

One major difference between meiosis and mitosis is

meiosis has to separate homologous chromosomes, mitosis does not.

Ploidy

number of sets of chromosomes in a cell

A karyotype is most like

photographs of every couple at a high school prom.

Indepdent orientation of chromosomes at metaphase I results in an increase in the number of

possible combination of characteristics.

The letter "n" is used to

represent a complete set of chromosomes regardless of the species. Diploid organism w/ homologous pairs of chromosomes is designated "2n".

Genetic variation results from ___________ reproduction, while ___________ reproduction limits genetic variation and thus, does not require meiosis.

sexual; asexual

Meiosis II is similar to mitosis in that

sister chromatids separate during anaphase

Synapsis

the fusion of chromosome pairs at the start of meiosis.

Tetrads

the paired chromosomes consisting of four chromatids

Meiosis II

the second phase of meiosis consisting of chromatids separating, along with the two diploid cells splitting in two

heredity or inheritance

the transmission of traits from one generation to the next

Homologous chromosomes are not identical because

they have different alleles of the same genes.

A gene codes for a(n) _________ and a form of a this is called a(n) ______.

trait; allele

Which are more similar, two sister chromatids or two homologous chromosomes?

two homologous chromosomes

Even though siblings have the same parents, they don't all have the same traits. This demonstrates

variation.