Flashcards in Chapter 6.1 Deck (35):
Identify 2 ways in which sexual reproduction is different from asexual reproduction.
- Requires 2 parents
- Produces offspring genetically different from each other, both parents and any member of their species
Why does genetic diversity within a species more advantageous than a species with no genetic diversity?
Organisms will have combinations of genes from parents which may allow it to better cope with changes in its environment
What kind of cells are in your body that contain 46 (2x23) chromosomes?
What are gametes?
Specialized cells necessary for reproduction
What are female gametes called?
What are male gametes called?
How are gametes different from all other body cells?
Gametes carry haploid chromosomes
What happens to the number of chromosomes during fertilization?
Number of chromosomes becomes 46.
(Haploid male and female gametes combine, forming a diploid cell (a zygote) with 46 chromosomes)
What is the difference between a zygote and an embryo?
A zygote undergoes mitosis and cell division and develops into an embryo
What is meiosis?
The process that produces sperm and eggs
What happens in Prophase I?
Homologous chromosomes pair up and non-sister chromatids exchange genetic material (AKA Crossing Over)
What happens in Metaphase I?
Homologous chromosomes pair up at the equator
What happens in Anaphase I?
Homologous chromosomes seperate and are pulled to opposite poles by spindle fibres.
Independant assortment occurs.
What happens in Telophase I?
One chromosome from each homologous pair is at each pole of the cell
What happens in interkenesis?
The stage between cell divisions.
The cell grows and makes proteins. Similar to interphase in mitosis but there is no replication of DNA
What happens in Prophase II?
There is one chromosome of the homologous pair in each cell
What happens in Metaphase II?
The chromosomes form a single line across the middle
What happens in Anaphase II?
Sister chromatids move to opposite poles of the cell
What happens in Telophase II?
Spindle fibres begin to disappear, and a nuclear membrane forms around each set of chromosomes
What happens in cytokenesis?
The 2 daughter cells are seperated.
What is the result of meiosis I?
2 diploid cells, each with 46 chromosomes
What is the result of meiosis II?
4 haploid cells, each with 23 chromosomes
What are the 2 main differences between mitosis and meiosis?
Mitosis: Chromosomes line up along the equator and sister chromatids are pulled apart.
Meiosis: A pair of matching chromosomes line up at the equator and each chromosome is pulled apart.
Mitosis: 2 daughter cells are produced, each with 46 chromosomes.
Meiosis: 4 daughter cells are produced, each with 23 chromosomes
What are the main differences between Meiosis I and II?
Meiosis I: Homologous chromosomes are pulled to opposite poles of the cell.
Meiosis II: Sister chromatids are pulled to opposite poles of the cell.
Meiosis I: 2 daughter cells are produced
Meiosis II: 4 haploid cells are produced
Meiosis I: DNA is replicated before process begins
Meiosis II: DNA is nor replicated before process begins
What 3 events in meiosis help to increase the genetic diversity of an organism?
Crossing over, independent assortment and gamete formation
What is happens in crossing over?
Parts of non-sister chromatids exchange segments of DNA
What happens in independent assortment?
Homologous pairs of chromosomes seperate and sort themselves into daughter cells
What happens in gamete formation?
Meiosis results in 4 haploid cell sperm cells for males and one haploid egg for females
Why don't women produce the same amount of gametes as men?
After meiosis II, 3 of the female gamete cells will disintegrate. The remaining one, the largest, is available for fertilization
What types of mutations may occur in meiosis? What affect can these mutations have on an organism?
Parts of a chromosome can be lost, duplicated, or moved within a chromosome or moved to another chromosome.
They affect many genes in the chromosome and change the proteins made by those genes.
What causes chromosome mutations?
Mutagens - such as radiation or chemicals
During Meiosis I - when homologous chromosomes fail to seperate
During Meiosis II - when sister chromatids fail to seperate
Why are many chromosome mutations not passed from one generation to another?
Offspring either fails to develop or does not reach reproductive age and adulthood
What is a karyotype?
A "picture" that shows all of a person's chromosomes arranged in a particular order
What is a karyotype used for?
Diagnose genetic disorders