U3L4: Meiosis

Use the drop-down menus to complete the statements. Meiosis involves ___ cell divisions. In meiosis, the original cell is ___. This means it has ___ sets of chromosomes. Meiosis results in ___ cells. Each of these cells contains ___ chromosomes.

2 diploid; 2 4 haploid; 23 chromosomes

How many chromosomes does a child inherit from his or her parents? 23 from the mother and 23 from the father 46 from the mother 46 from the father 46 from the mother and 46 from the father

23 from the mother and 23 from the father

There are two types of cell division. The first (A) produces cells that are identical to the original cell. The second (B) produces cells that are different from the original cell. Which type of cell division do you think is responsible for these processes? ___ replacement of damaged skin cells ___ growth of an organism ___ production of sperm and egg cells

A A B

Which best illustrates how Gregor Mendel used creativity that lead to scientific discovery? He noticed that traits were passed on from parents to offspring. He chose a parent generation and carefully studied its traits. He used pea plants to study the patterns of heredity. He observed how specific traits were passed from parent to offspring.

He used pea plants to study the patterns of heredity.

Identify the types of genetic recombination. ___ occurs in metaphase I. ___ occurs during sexual reproduction. ___ is random chromosome alignment resulting in variation. ___ occurs in prophase I. ___ fuses gametes to form offspring with genes from each parent. ___ exchanges genetic information between non-sister chromatids.

Independent assortment Fertilization Independent assortment Crossing over Fertilization Crossing over

Why is meiosis important for organisms? It allows for genetic variation among organisms. It determines which genes are dominant and which are recessive. It produces genetically identical cells. It provides a means of asexual reproduction.

It allows for genetic variation among organisms.

Explain the relationship between crossing over and genetic variation.

What information did you include in your response? Crossing over is the process by which genetic material is exchanged by non-sister chromatids during meiosis. Crossing over results in a new combination of genetic information for the cell for a specific trait. Crossing over ensures that organisms are not identical from generation to generation. Genetic recombination allows for a variation in genetic material that is passed through the generations.

Explain how independent assortment occurs in cells and explain its importance.

What information did you include in your response? Independent Assortment is the second law of inheritance. Traits are passed from parents to offspring independently of one another. Independent assortment is random and occurs during Metaphase I of meiosis. There are two possible alignments for the chromosomes. Since the alignments are random and not assigned, genetic variation occurs.

gamete

a male or female sex cell (male sperm and female egg)

meiosis

a process involving two cell divisions, in which one diploid cell produces four haploid cells with half the number of chromosomes as the parent cell

Identify the phases of meiosis I described below. ___ Homologous chromosomes are separated. ___ Homologous chromosome are paired. ___ Nuclear envelopes form around separated chromosomes. ___ The centrosome replicates.

anaphase I prophase I telophase I metaphase I

The diagram illustrates one method of genetic recombination. Which method of genetic recombination is illustrated in the diagram? crossing over independent assortment fertilization tetrad formation

crossing over

Which three processes are methods of genetic recombination? natural selection, crossing over, and independent assortment crossing over, independent assortment, and fertilization independent assortment, fertilization, and natural selection fertilization, natural selection, and crossing over

crossing over, independent assortment, and fertilization

Which process of genetic recombination involves genes from both parents? crossing over independent assortment fertilization tetrad formation

fertilization

Which consist of sperm cells and egg cells? gametes tetrads diploids chromosomes

gametes

haploid

having one set of chromosomes

diploid

having two sets of chromosomes

Genetic variation occurs through genetic recombination. Which method of genetic recombination is illustrated in the diagram? independent assortment fertilization crossing over sexual reproduction

independent assortment

Identify the phases of Meiosis II described below. ___ Chromosomes are lined up by spindle fibers. ___ Nuclear envelope forms around each set of DNA. ___ Sister chromatids are pulled apart. ___ Centromeres move toward the poles of the cell.

metaphase II telophase II anaphase II prophase II

During which phase of meiosis does crossing over of chromosomes occur? prophase I metaphase I anaphase I telophase I

prophase I

crossing over

the process by which genetic material is exchanged by non-sister chromatids during prophase I of meiosis

law of independent assortment

the second law of inheritance, which states that traits are passed from parents to offspring independently of one another

How many cell divisions occur during meiosis? one two three four

two