AP Bio Chapter 13
How many times do the chromosomes duplicate?
1
How many times does the cell divide in meiosis?
2
How many daughter cells are formed?
2 in M1, 4 in M2
What are homologs?
2 of the same chromosome
What is the chromosome number of the daughter cells of meiosis?
23
because humans have 46 chromosomes or 23 homologous pairs, what is the number of possible gametes that can be formed due to independent assortment of chromosomes?
2^23 (8.4 million)
How many chromosomes are in each cell at the end of the first meiotic division?
6
How many chromosomes does the cell on the previous page have? How many homologous pairs? How many chromatids? Is this cell haploid or diploid?
6 1 12 diploid
random fertilization
70 trillion different combinations
The muscle cells of a dog have 78 chromosomes. Fill in the correct chromosome number for the following cells in a dog: bone cell _____, sperm _____, haploid cell _____, somatic cell ____, and zygote ____.
78, 39, 39, 78, 78
How many chromosomes are there in human cells? What is a chromosome?
A chromosome is a package of DNA, there are 46
locus
A gene's specific location along a chromosome
somatic cells
All cells in the body except for the gametes
What are alleles? Give an example.
Alleles are versions of a gene. Eye color genes are an example.
What will separate the first division in meiosis 1?
Anaphase 1 and Telophase 1
During which division is the chromosome number reduced?
Anaphase 2
Which type of reproduction will result in genetically identical offspring?
Asexual reproduction
What is crossing over?
Combination of DNA by exchanging parts of chromosomes
crossing over
DNA combines by attaching one homolog to the other
synapsis
Duplicate homologs line up (in prophase 1)
gene
Hereditary units containing DNA
Explain the physical events of crossing over.
Homologous non sister chromatids line up. There are DNA breaks in specific spots. The chromosomes condense and attach by the forming synaptonemal complex. The DNA joins, producing crossovers, the specific spot called chiasmata.
What occurs in synapsis? When does it occur?
Homologs line up for crossing over. It is in prophase 1.
How is the arrangement of the chromosomes different from the metaphase of mitosis?
In mitosis, the chromosomes aren't connected because it is an exact copy, so there is only one type.
What are 2 things that can be determined from a karyotype?
It can determine if there are and deformations or an abnormal number of chromosomes.
What is a karyotype? How is it prepared?
It is a picture of chromosomes in order by length. Karyotypes are from isolated somatic cells, then drugged to induce mitosis. In metaphase, chromosomes are stained and then photographed. Then a computer arranges them in order.
What happens to the chromosome number in meiosis?
It is reduced
By what process are gametes produced?
Meiosis
Where are the gametes of an animal produced?
Ovaries and testes
gametes
Reproductive cells
Distinguish between sex chromosomes and autosomes. How many of each are found in human cells?
Sex chromosome: X&Y chromosomes. 2 Autosome: All the rest. 44
Explain what is meant by homologous chromosomes.
The 2 chromosomes that have the exact same staining, centromere placement, and length.
genome
The genetic material
What is the purpose of meiosis?
To make a haploid cell for reproduction
What is the purpose of meiosis?
To make haploid cells for reproduction
alternation of generations. a) what does this mean? b) what are the 2 generations? c) which generation is haploid, and which is diploid?
a) a different type of life cycle that alternates between haploid and diploid. b) haploid and diploid. c) diploid, haploid.
independent assortment of chromosomes
creates genetic variation
crossing over
crossovers can be different every time
liver cell
diploid
skin cell
diploid
somatic cell
diploid
stem cell
diploid
zygote
diploid
Meiosis always begins with cells that are ______, and as a result of meiosis, daughter cells are formed that are always _______.
diploid, haploid
female gamete
egg
Are the resultant daughter cells haploid or diploid?
haploid
egg cell
haploid
gamete
haploid
sperm
haploid
How does a somatic cell compare to a gamete in terms of chromosome number?
it has twice as many chromosomes
By what process are eggs formed?
meiosis
Which process reduces the chromosome number of daughter cells?
meiosis
By what process are the damaged cells in a wound replaced?
mitosis
By what process does a zygote develop into a multicellular organism
mitosis
In which process are identical daughter cells produced?
mitosis
sexual reproduction
reproduction with gametes from 2 parents (combination of DNA)
asexual reproduction
reproduction without gametes (cloning)
male gamete
sperm
chiasmata
the points where the crossovers occur
What separates during meiosis 2?
the sister chromatids