Chapter 10 Flashcards
How many chromosomes does each human body cell have?
23 pair
Haploid
A cell with n chromosomes (only 1 allele for each trait) 23
Diploid
Cell that contains 2n chromosomes (only 2 alleles for each trait) 46
What makes an organism more complex?
The amount of genes or into on the chromosomes
Homologous chromosomes
One of the two paired chromosomes, one from each parent
Homologous pair
Same chromosome from each parent
Similarities and differences between a pair of homologous chromosomes?
- same length (because they have the same genes)
- same centromere position
- carry genes that control the same inherited traits
- different possible variation of the gene (allele) (moms eyes could be brown, dads eyes could be blue)
Gene
Segment of DNA
Allele
Variations of a gene
Ex. Hair colors
How many alleles per gene in a haploid cell
One allele for every gene
Why are gametes produced?
To maintain the same number of chromosomes from generation to generation
Gonad
Sex organ
What happens when gametes combine in fertilization?
The number of chromosomes is restored
What makes gametes
Meiosis
Zygote
Fertilized egg
Fertilization
When the egg and sperm combine
What happens in meiosis I
- chromosome number is reduced by half through the separation of homologous chromosomes
Interphase
- happens once
- growth and development
- DNA copied
- final prep/checkpoint
Prophase I
- chromosomes coil
- pairing of homologous chromosomes occurs
- nuclear envelope breaks down
- spindles farm
- crossing over
Crossing over
Chromosomal segments are exchanged between a pair of homologous chromosomes
What happens because of crossing over
- new combo of genetics
- exchange of genetic information
- possible mutations
How many chromatids in a chromosome?
2
Metaphase I
- spindle fibers line the homologous chromosomes up in the middle
- random assortment when they line up
Anaphase I
- homologous chromosomes splits and move to polar poles (not making any more chromosomes)
Telophase I
- spindles break down
- chromosomes uncoil and form two nuclei
- cell divides
- end up with 2 haploid cells
Prophase II
- chromosomes condense
- spindle apparatus forms and attaches
- nuclear envelope disappears