Transcript 10-for-meiosis
Chapter 10 Sexual Reproduction and Genetics
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Chapter 10 Sexual Reproduction and Genetics 10.1 Meiosis
Chromosomes and Chromosome Number
Chromosomes – structures that carry genetic information from one generation to the next.
Homologous chromosomes — chromosomes that carry information for the same genes, not necessarily the same information, but for the same gene. Same length Same centromere position Carry genes that control the same inherited traits
Chapter 10 Sexual Reproduction and Genetics
Human body cells have 46 chromosomes, 23 pairs Each pair has 1 chromosome from each parent From male parent Gene controlling ear lobes From female parent Gene controlling ear lobes Info - attached Info - unattached Ex.
Gene controlling chin shape Info – cleft chin Gene controlling chin shape Info – non-cleft chin
Chapter 10 Sexual Reproduction and Genetics
Haploid and Diploid Cells Haploid cell contains only 1 chromosome from each pair; chromosome number =
n
Ex. Sex cells (gametes) egg and sperm Human gametes contain 23 chromosomes.
Diploid cell contains both chromosomes from each pair; chromosomes number = 2
n
Ex. Skin cells, liver cells, muscle cells, etc.
Chapter 10 Sexual Reproduction and Genetics
Meiosis sexual life cycles involve meiosis .
Meiosis produces haploid gametes
with half the # of chromosomes
When gametes combine in fertilization, the diploid number of chromosomes is restored.
Chapter 10 Sexual Reproduction and Genetics
Meiosis
has 2 consecutive nuclear divisions Meiosis I and Meiosis II During interphase before meiosis I, chromosomes replicate
Chapter 10 Sexual Reproduction and Genetics
Prophase I Pairing of homologous chromosomes each consisting of 2 chromatids Crossing over —chromosomal segments are exchanged between homologous pairs. Allows for genetic variation.
Chapter 10 Sexual Reproduction and Genetics
Metaphase I spindle fibers, which are attached to centromeres, line up homologous chromosomes at the equatorial plate
Chapter 10 Sexual Reproduction and Genetics
Anaphase I homologous pairs separate and begin moving toward opposite poles
Chapter 10 Sexual Reproduction and Genetics
Telophase I spindles break down chromosomes uncoil and form two nuclei cell membrane pinches in
Cytokinesis occurs producing two new cells, each with ½ the number of chromosomes of the original cell….reduction division!!!! Important – THERE IS NO DNA REPLICATION BETWEEN MEIOSIS I AND MEIOSIS II.
Chapter 10 Sexual Reproduction and Genetics
Meiosis II
Prophase II •Chromosomes condense and spindle forms
Chapter 10 Sexual Reproduction and Genetics
Metaphase II • centromeres that are attached to spindle fibers line up at the equator.
Chapter 10 Sexual Reproduction and Genetics
Anaphase II sister chromatids separate at the centromeres and begin moving toward opposite poles of the cell.
Chapter 10 Sexual Reproduction and Genetics
Telophase II •chromosomes reach the poles •nuclear membrane and nuclei reform
Chapter 10 Sexual Reproduction and Genetics
Cytokinesis results in four haploid cells, each with
n
number of chromosomes.
Chapter 10 Sexual Reproduction and Genetics
Chapter 10 Sexual Reproduction and Genetics
Meiosis Provides Variation Depending on how the chromosomes line up at the equator, four gametes with four different combinations of chromosomes can result.
Genetic variation occurs during crossing over and during fertilization, when gametes randomly combine.
Chapter 10 Sexual Reproduction and Genetics
Sexual Reproduction vs. Asexual Reproduction
Asexual reproduction – new organism inherits all of it’s chromosomes from a single parent and is genetically identical to it’s parent Sexual reproduction new organism inherits it’s chromosomes from 2 different parents which allows for genetic variation
Chapter 10 Sexual Reproduction and Genetics Chapter Diagnostic Questions
Which symbol is used to represent the number of chromosomes in a gamete? A.
# B.
x C.
r D.
n
A 0% 0% B
1.
2.
3.
4.
A B C D
0% C 0% D
Chapter 10 Sexual Reproduction and Genetics 10.1 Formative Questions
Segments of DNA that control the production of proteins are called _______.
A.
chromatids B.
chromosomes C.
genes D.
traits
A 0% 0% B
1.
2.
3.
4.
A B C D
0% C 0% D
Chapter 10 Sexual Reproduction and Genetics 10.1 Formative Questions
What is the term for a pair of chromosomes that have the same length, same centromere position, and carry genes that control the same traits?
A.
diploid B.
heterozygous C.
homozygous D.
homologous 1.
2.
3.
4.
A B C D
A 0% 0% B 0% C 0% D
Chapter 10 Sexual Reproduction and Genetics 10.1 Formative Questions
How does the number of chromosomes in gametes compare with the number of chromosomes in body cells?
A.
Gametes have 1/4 the number of chromosomes.
B.
Gametes have 1/2 the number of chromosomes.
C.
Gametes have the same number of chromosomes.
D.
Gametes have twice as many chromosomes.
A 0% 0% B
1.
2.
3.
4.
C
A B C D
0% D
Chapter 10 Sexual Reproduction and Genetics 10.1 Formative Questions
What type of organisms only reproduce asexually?
A.
bacteria B.
protists C.
plants D.
simple animals
A 0% 0% B
1.
2.
3.
4.
A B C D
0% C 0% D
Chapter 10 Sexual Reproduction and Genetics Chapter Assessment Questions
How many chromosomes would a cell have during metaphase I of meiosis if it has 12 chromosomes during interphase?
A.
6 B.
12 C.
24 D.
36
A 0% 0% B
1.
2.
3.
4.
A B C D
0% C 0% D
Chapter 10 Sexual Reproduction and Genetics Chapter Assessment Questions
Which stage of meiosis is illustrated? A.
prophase I B.
interphase C.
anaphase I D.
anaphase II 1.
2.
3.
4.
A B C D
A 0% 0% B 0% C 0% D
Chapter 10 Sexual Reproduction and Genetics Chapter Assessment Questions
What is the next step for the chromosomes illustrated? A.
Chromosomes replicate.
B.
Chromosomes move to opposite poles.
C.
Chromosomes uncoil and form two nuclei.
D.
Chromosomes line up at the equator.
1.
2.
3.
4.
A B C D
A 0% 0% B 0% C 0% D
Chapter 10 Sexual Reproduction and Genetics Standardized Test Practice
What is this process called?
A.
fertilization B.
gamete formation C.
inheritance D.
reproduction 1.
2.
3.
4.
A B C D
A 0% 0% B 0% C 0% D
Chapter 10 Sexual Reproduction and Genetics Standardized Test Practice
Before meiosis I, the sister chromatids of this chromosome were identical. What process caused a change in a section of one chromatid?
A.
DNA replication B.
crossing over C.
synapsis D.
telophase 1.
2.
3.
4.
A B C D
A 0% 0% B 0% C 0% D
Chapter 10 Sexual Reproduction and Genetics Standardized Test Practice
At what stage is the chromosome number reduced from
2n
to
n
?
A.
prophase I B.
metaphase I C.
anaphase I D.
meiosis II
A 0% 0% B 0% C 0% D
1.
2.
3.
4.
A B C D
Chapter 10 Sexual Reproduction and Genetics Standardized Test Practice
To which step in this process does the law of segregation apply?
A.
grows into plant B.
gamete formation C.
fertilization D.
seed development 1.
2.
3.
4.
A B C D
A 0% 0% B 0% C 0% D
Chapter 10 Sexual Reproduction and Genetics Vocabulary
Section 1
gene homologous chromosome gamete haploid fertilization diploid meiosis crossing over
Chapter 10 Sexual Reproduction and Genetics Animation
Visualizing Meiosis I and Meiosis II Generations