UNIT 5: topics 1 + 2 "Meiosis and Genetic Diversity"

What 3 things can lead to genetic variation

-crossing over -mutations -independent assortment

There are _____ rounds in meiosis

2

At the end of meiosis how many chromosomes are there?

23

At the end of meiosis how many cells are there?

4

How many chromosomes are in the beginning of meiosis?

46

In what phase do homologous chromosomes separate?

Anaphase I

If meiosis halves the number of chromosomes in gametes, then how do the cells return to normal chromosome number (i.e. how do somatic cells stem from these gametic cells)?

At the end of meiosis, four haploid daughter cells (gametes) are created. Then, during the fertilization process, when the egg and sperm combine, each gamete from either parent combine to provide the 46 chromosomes needed.

How are mitosis and meiosis similar?

Both processes include the breakdown of the nuclear membrane, the separation of genetic material into two groups, followed by cell division and the reformation of the nuclear membrane in each cells.

what is exchanged during crossing over

DNA

TRUE OR FALSE: meiosis results in daughter cells with the same number of chromosome as the parent.

FALSE: daughter cells in meiosis result in half the number of chromosomes (haploid)

When would it be advantageous to produce an organism through asexual reproduction?

In terms of agricultural studies, being able to produce something asexually would benefit the farmer immensely. If they were to have a plant with all of the desired characteristics, through asexual reproduction, they could maintain those genes throughout the rest of the crop.

How many cells does meiosis start with?

In the beginning of meiosis there is one cell

How are mitosis and meiosis different?

Mitosis- starts with one parent cell and ends with two daughter cells The cells are copies of the parent cell The cells are diploid (contain 2 sets of chromosomes) Produces somatic cells (body cells) There is one division Meiosis- starts with two parent cells and ends with four daughter cells The cells are genetically different from the parent cells The cells are haploid (contain 1 set of chromosomes) Produces gametes (sex cells- sperm and egg) There are two divisions

TRUE OR FALSE: meiosis involves two rounds

TRUE

If the eggs of Drosophilia have two chromosomes, how many chromosomes do their diploid cell contain?

Their diploid cells contain 4.

If an organism is 2n = 24 what is their haploid number?

Their haploid number would be n = 12

How is it possible that every gamete produced through meiosis has a unique combination of DNA?

Through the process of recombination (crossing over) that occurs in prophase I, genetic diversity throughout the gametes is achieved. (Additionally, independent assortment has a hand in the process of producing unique genes in the gametes as well).

How are traits passed from parents to offspring?

Traits are passed from parent to offspring through GENES

How are the offspring produced in asexual reproduction different that that of those in sexual reproduction?

When an organism reproduces asexually, they go through a process called mitosis. Mitosis is a similar process to meiosis in that it produces genetic offspring, however, the offspring are genetically identical to the parent. Through meiosis (sexual reproduction) the gametes produced are genetically unique.

What is the difference between asexual and sexual reproduction

asexual: single individual, no fusion of gametes, clones, mutations are ONLY genetic diversity, produce asexually through mitosis sexual: two parents, offspring are unique, combos of genes from parents, genetic variety

What are the two types of chromosomes

autosomes and sex chromosomes

In meiosis I, homologous chromosomes exchange genetic material via a process called __________ ___________.

crossing over (recombination)

In what cells does meiosis occur?

gametic cells

Meiosis followed by fertilization ensures ____________.

genetic variety

How are chromosomes in karyotypes ordered

in order from largest to smallest, with the sex chromosomes at the end

in what phase do the tetrads line up at the chiasmata

metaphase I

In what phase do chromosomes connect and form tetrads, and perform crossing over?

prophase I

what are the "key events" in meiosis

prophase I, Metaphase I, Anaphase I

how are prophase I and prophase II different

recombination only occurs in prophase I