Genes, Alleles, and meiosis Study Guide

Compare and contrast mitosis and meiosis. 2 identical diploid cells 4 unique haploid cells one duplication of DNA, one division one duplication, two divisions a form a asexual reproduction 1st stage in sexual reproduction

How are human egg cells similar to human sperm cells? both are haploid

combinations different from the original How many chromosomes does a cell have after meiosis (as compared to a parent cell)? ½ , with gene combinations different from the original

What happens during oogenesis in humans? Meiosis in females producing 3 inactive polar bodies and one egg cell

What is the diploid number of chromosomes in a human cell? 46

A sex cell (sperm cell or egg cell) Define gamete. A sex cell (sperm cell or egg cell)

Define zygote. Single cell formed when the egg and sperm cell unite during fertilization

If an organism has 20 chromosomes for his normal diploid number, then how many chromosomes will it have after meiosis? 10

Describe the process of fertilization. Sperm cell and egg cell unite to form a zygote

What happens in the process of “crossing over?” chromatids of the homologous chromosomes cross over one another and crossed sections exchange

Define Heredity: passing of characteristics from parent to offspring

What happens to the diploid number of chromosomes that an organism has after it undergoes meiosis? It is cut in half

What is the chromosome arrangement for the picture above? (n + n  2n) Fertilization

Complex organisms produce gametes (egg and sperm) that unite during fertilization, forming a single cell known as _______. Zygote

The picture above demonstrates what concept? fertilization

The picture above demonstrates what concept? Crossing-over

The picture shown above demonstrates what concept? meiosis

Different forms of a gene that determine traits What is an allele? Different forms of a gene that determine traits

How is prophase I of meiosis different from prophase of mitosis? Prophase I of meiosis has: crossing over, which shuffles chromosomes between homologs Formation of tetrads(pairs of homologous chromosomes)

Separating paired homologous chromosomes occurs during what phase? Anaphase1

In meiosis I, what happens to the total number of chromosomes in the cell? It is cut in half

Which stage of meiosis, I or II, is more similar to mitosis Which stage of meiosis, I or II, is more similar to mitosis? How is it different? Meiosis II is more similar to mitosis- both separate duplicated chromosomes

Crossing over in prophase I shuffles chromosomes between homologs How is the genetic variation seen in gene pools of various organisms best explained? Crossing over in prophase I shuffles chromosomes between homologs anaphase II separates duplicated chromosomes to 4 cells which then contain unique combinations of alleles

In mitosis, duplicated chromosomes divide and each of the two cells produced contain a full set of the duplicated genetic material. What is contained in the two cells produced at the end of meiosis I? Meiosis II? Meiosis I- half of the homologous chromosome pairs that are now unique are randomly sorted to the two cells produced; the chromosomes remain duplicated Meiosis II- duplicated chromosomes are separated to produce 4 cells containing unique allele combinations

Sister chromatids separate to different daughter cells at the end of meiosis II. Does this change the chromosome number from the number in each cell at the end of meiosis I? No, chromosome number is the same because it is duplicated chromosomes that are separated