meiosis

Question 1

when does meiosis occur

Answer 1

during gametogenesis

Question 2

what happens in meiosis i

Answer 2

a single cell forms two haploid cells (chr # is halved)

Question 3

what happens in meiosis ii

Answer 3

each of the haploid cells form two haploid cells

Question 4

describe interphase

Answer 4

dna replication takes place to double the amount of genetic material

Question 5

describe prophase i

Answer 5

chromatin network unwinds to form distinct chromosomes
crossing over takes place between adjacent chromatids of homologous chromosomes leading to the exchange of genetic material

Question 6

what is chiasma

Answer 6

point of overlap of chromatids during crossing over

Question 7

describe metaphase i

Answer 7

chr become arranged randomly along the equator in homologous pairs
they are attached to spindle fibers formed by centrioles

Question 8

Why is meiosis important?

Answer 8

Meiosis is crucial for sexual reproduction as it reduces the number of chromosomes to half in gametes cells, maintains a constant number of chromosomes, and prevents the doubling effect of fertilization. Additionally, the step of crossing over in meiosis increases genetic variation from parent to offspring.

Question 9

what is meiosis

Answer 9

Meiosis is a cellular process that produces 4 unidentical cells with half the number of chromosomes as the original, and it’s responsible for the formation of gametes through gametogenesis.

Question 10

What happens during crossing over in meiosis?

Answer 10

Crossing over occurs in prophase 1 between homologous pairs. One chromatid of each chromosome overlaps with its adjacent chromatid at a point called the “chiasma.” Genetic material is swapped between the chromatids, increasing genetic variation.

Question 11

What is the difference between somatic cells and sex cells?

Answer 11

Somatic cells, except for sperm and ovum/egg cells, are found throughout the body and have 46 chromosomes arranged in 23 pairs, referred to as diploid. Sex cells, such as sperm and ovum, contain only 23 chromosomes and are haploid.

Question 12

How are karyotypes characterized, and what information do they provide?

Answer 12

Karyotypes are graphical representations of all 23 chromosome pairs found in somatic cells. They reveal three key pieces of information about an organism: the type of organism, its gender, and any genetic disorders present.

Question 13

What are autosomes and gonosomes in a karyotype?

Answer 13

Autosomes are the first 22 pairs of chromosomes, which are identical, while the last pair is known as gonosomes. Gonosomes determine an individual’s gender and can be represented by XX chromosomes for females or XY chromosomes for males.

Question 14

What is nondisjunction, and when does it occur during meiosis?

Answer 14

Nondisjunction occurs during anaphase 1 or 2 of meiosis when chromosomes or chromatids fail to separate equally, resulting in an unequal distribution of chromosomes or chromatids in the resulting cells.

Question 15

What is the difference between aneuploidy and polyploidy?

Answer 15

Aneuploidy refers to the presence or absence of an extra set of chromosomes, whereas polyploidy refers to the presence or absence of extra sets of chromosomes.

Question 16

What causes Down syndrome, and how does it affect chromosome count?

Answer 16

Down syndrome is caused by the presence of an extra chromosome in pair 21, resulting in a total of 47 chromosomes instead of the usual 46. This condition, also known as “Trisomy 21,” is characterized by specific physical features such as upward slanted eyes, depressed nasal cavity, mental retardation, abnormal ear shape, and heart defects.