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Ch13 Meiosis
BIO181 BIO 181 Obermiller
56
Biology
Undergraduate 2
06/14/2012

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Term
What do you call a cell that contains only one set of chromosomes?
Definition
Haploid
Term
What term is used to describe traits passed down from generation to generation?
Definition
Heredity
Term
What branch of biology is dedicated to the study of heredity and variation?
Definition
Genetics
Term
What do you call a cell that contains two sets of chromosomes?
Definition
Diploid
Term
In what phase of meiosis does crossing over occur?
Definition
Prophase I
Term
What gene is only found on the X chromosome?
Definition
X-linked
Term
What do you call observable differences in organisms between generations?
Definition
Variation
Term
What do you call sex cells?
Definition
Gametes
Term
What are non-sex chromosomes called?
Definition
Autosome
Term
In what phase of meiosis do the sister chromatids separate?
Definition
Anaphase II
Term
In what phase of meiosis do the homologous chromosomes separate?
Definition
Anaphase I
Term
What is the ploid representation after S phase in humans?
Definition

4N

 

Term
What do you call the identification of chromosomes based on their banding pattern, centromere position, and size?
Definition
Karyotype
Term
What is the term used to describe the random chance for each gamete to meet and form a zygote?
Definition
Random Fertilization
Term
What is the physical location of a gene on a chromosome called?
Definition
Locus
Term
What do you call chromosomes that contain the same genes and thus are the same size, have the same centromere position, and the same banding pattern?
Definition
Homologous
Term
What term is used to describe a fertilized egg while it is still a single cell?
Definition
Zygote
Term
A disease that is caused by the absence of the clotting agent factor VIII?
Definition
Hemophilia
Term
What results from fusing of sex cells?
Definition
Fertilization
Term
What do you call the exchange of genetic information between homologous chromosome during prophase I of meiosis?
Definition
Crossing Over
Term
What is the nucleic acid code, made from DNA, in the nucleus and transported into the cytoplasm, to make proteins?
Definition
mRNA
Term
What type of cells include all cells except for sex cells?
Definition
Somatic
Term
What is the central dogma of molecular biology?
Definition
DNA makes RNA, which makes protein.

Main thesis of molecular inheritance.
Term
Why are offspring different from their parents?
Definition
Each parent contributes half of their chromosomes
Term
What genetic information is made by both parents?
Definition
Sperm and egg cells both contain half the number of chromosomes found in any other human cell--23, as opposed to 46. Chromosomes contain tighly wound coils of DNA, sections of which are referred to as "genes."
Term
What is the study of heredity and variation called?
Definition
Genetics
Term
What is the royal disease?
Definition
Hemophilia - disease which results in the inability of the body to stop bleeding from a wound
Term
What is the molecular cause of the royal disease?
Definition
X-linked recessive inheritance
Term
What makes the inheritance of royal disease unique?
Definition
The gene for clotting factor VIII is on the X chromosome which results in only males getting the disease because they only inherit 1 X chromosomes where as females inherit 2 X chromosomes
Term
How was this trait fixed in the population? (Royal disease)
Definition
Inbreeding
Term
Why is inbreeding a "bad" thing?
Definition
Variation is important!

Breeding within families reduces variation and retains traits (both good and bad) - developing genetic abnormalities
Term
What is the difference between a somatic cell and a sex cell?
Definition
Somatic (body) cells are important for growth and healing. Contain 46 chromosomes; 23 pairs.

Sex cells (gametes) - 23 chromosomes from each parent; 1/2 genetic material.
Term
What is the difference between a homologous chromosome and a sister chromatid?
Definition
Homologous chromosomes have the same size, centromere position and staining pattern.

Sister chromatids are identical copies attached to each other by centromeres.
Term
How do biologists identify homologous chromosomes?
Definition
Size
Position of centromere
Branding pattern
Term
Why are they homologous? (chromosomes)
Definition
They have the same size, centromere position and staining pattern
Term
What is the only way a normal human can have a pair of non-homologous chromosomes?
Definition
Sex chromosomes (XY)
Term
What is the difference between haploid and diploid cells?
Definition
Haploid - contains 1 set of chromosomes

Diploid - contains 2 sets of chromosomes
Term
Provide an example of haploid and diploid cells in humans.
Definition
Haploid: Gametes (n=23)

Diploid: Somatic (2n=46)
Term
What stage of the life cycle are the majority of our cells in?
Definition
Interphase
Term
How is there so much variation among people?
Definition
Each gamete contains half of the chromosomes of each parent. The fertilization, chromosomes assortment, and synapsis all occur randomly. These random variables promote variation among people.
Term
What are the three things that contribute to variation among people?
Definition
Independent assortment
Crossing over
Random fertilization
Term
What is independent assortment?

When does it occur?

How does it contribute to variation?
Definition
Each pair of homologous chromosomes randomly assorts on the metaphase plate.

Occurs during Metaphase

The pairs could assort in any number of ways
Term
What is crossing over?

When does it occur?

How does it contribute to variation?
Definition
Genes are passed between arms of homolgous chromosomes.

Occurs during Prophase I

These genes could be exchanged in any number of ways depending on how the chromosomes and tetrads connected
Term
What are the stages of meiosis?
Definition
Meiosis I:
Prophase I
Metaphase I
Anaphase I
Telophase I

Meiosis II:
Prophase II
Metaphase II
Anaphase II
Telophase II
Term
What occurs in Prophase I?
Definition
Chromosomes condense Synapsis occurs (crossing over—genetic material exchanged between homologous chromosomes) **appear as tetrads

Centrosomes move apart and spindles form Nuclear envelope breaks down
Term
What occurs in Metaphase I?
Definition
Centrosomes move to poles

Microtubules attach to each homologue at kinetochore Tetrads aligned on Metaphase plate
Term
What occurs in Anaphase I?
Definition
Homologous chromosomes separate and move toward poles

Sister chromatids remain attached
Term
What occurs in Telophase I?
Definition
Each pole has set of sister chromatids

Cleavage furrow begins to form

Nuclei may reform—Nuclear envelope forms

Beginning of cytokinesis
Term
What occurs in Prophase II?
Definition
No duplication occurs
Centrosomes move apart
Spindles form
Nuclear envelope breaks down
Term
What occurs in Metaphase II?
Definition
Centrosomes move to poles
Microtubules attach to chromatid at kinetochore
Chromatids aligned on metaphase plate
Term
What occurs in Anaphase II?
Definition
Sister chromatids separate at centromeres and move toward poles
Term
What occurs in Telophase II?
Definition
Cleavage furrow begins to form
Nuclear envelope starts to form Beginning of cytokinesis

Gametes: haploid daughter cells (n=23)
Term
When does crossing over occur?
Definition
Prophase I
Term
When do homologous chromosomes separate?
Definition
Anaphase I
Term
When do sister chromatids separate?
Definition
Anaphase II
Term
Discuss the major differences between mitosis and meiosis?
Definition
Mitosis:
# of divisions - One
Synapsis does not occur
Two diploid, genetically identical cells
Role - growth and tissue repair

Meiosis:
# of divisions - Two
Synapsis occurs during Prophase I
Four haploid cells with 1/2 chromosomes
Role - gametes
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