Chapter 9 Sex Repro & Meiosis Flashcards
Explain asexual reproduction.
DNA replicated, mitosis, identical offspring
What is sexual reproduction?
Two parents, meiosis, different offspring
Sexual reproduction produces ________ _________ among offspring. Which increases the chance that some offspring survive in ___________ __________.
Genetic diversity
Changing environments
What is diploid cells?
2n
contain two full sets of chromosomes
What does homologous pair mean?
A pair of chromosomes that are matching and look-alike and carry the same sequence of genes.
What is a karyotype?
size ordered chart of all of the chromosomes in the cell. All in metaphase
What are chromosomes 1 through 22 called?
Autosomes
What is the 23rd chromosome?
Sex chromosomes
What are alleles?
Alternative versions of the same gene
Each chromosome is paired with an equally sized chromosome with the exception of the X and Y, true or false?
True
What are gametes?
Sperm and egg cells
What type of cells are gametes?
Haploid sex cells
What does haploid mean?
N
Contain only one full set of genetic information instead of two
What is formed when two haploid cells fuse at fertilization?
Zygote
What type of cells is a zygote?
Diploid 2n
What are germ cells? What type of division do they use?
Special diploid cells in the ovaries and testes, produces gamete cells. Divide by meiosis.
What are somatic cells?
rest of the body’s diploid cells. Divide by mitosis.
In meiosis how many times does DNA replicate and how many times does the nucleus divide?
DNA replicates once, nucleus divides twice creating 4 haploid non-identical daughter cells
Gametes produced in meiosis are different because of three things:
Crossing over, independent assortment, random fertilization
When does crossing over occur, and what does that mean?
Prophase one. Two homologous chromosomes exchange genetic material
When does independent assortment occur and what does it do?
Metaphase one. Chromosome pairs align randomly.
What does random fertilization mean?
It takes two to reproduce, different parents
What is monozygotic?
When one embryo splits in two, resulting in separate identical babies
What is dizygotic?
Two separate sperm cells fertilize two separate eggs. Fraternal twins. Offspring looks different
Mitosis daughter cells contain ______ chromosomes.
Meiosis daughter cells contain ________ amount of chromosomes.
Same as parent
Half
In meiosis, what allows for crossing over?
Homologous pairing
Polyploidy means what?
Extra chromosome SETS
DEF-gamete with one or more complete sets of extra chromosomes
What is nondisjunction?
Gametes having just one extra or missing chromosomes. Usually occurs when chromosomes fail to separate in meiotic division.
What Is trisomy?
Child inherits 3 copies of Chromosome 21
