Chapter 7: Cellular Replication and Variation Flashcards
What is meiosis?
A two-phase type of cellular division in which the chromosome number of a cell is halved to the haploid number; meiosis is the basis of gamete formation in animals and spore formation in plants
What is a locus?
The position a gene occupies in a chromosome
What are alleles?
One of the different versions of the same gene (at the same locus) determined by small differences in the DNA sequence of the gene
What is a genotype?
The alleles present in the cells of an organism
What are chromatids?
A daughter strand of a duplicated chromosome that is joined by a centromere - (refer to figure 7.1.2 pg 141 for more detail)
What is an autosome?
A chromosome that is the same in both males and females of a species; autosomes do not include sex chromosomes
What is diploid (2n)?
Describes a cell or organism that has a genome comprising two copies of each chromosome, represented by 2n
What is haploid (n)?
Describes a cell or organism that has a genome that contains one copy of each chromosome, represented by n
What is interphase?
The stage between nuclear divisions
What are the inputs and outputs of meiosis?
Refer to figure 7.1.3 pg 142 for information
What is a synapsis?
The pairing of homologous chromosomes
What is a bivalent?
Visible bodies in a cell during prophase I of meiosis, which is made up of two homologous chromosomes joined together
What are chiasmata?
The point of contact between homologous chromosomes during prophase I of meiosis
What is cytokinesis?
The division of the cytoplasm
What is the process of meiosis I and II?
Refer to figure 7.1.4 pg 143 for information
What is crossing over?
An event during meiosis in which homologous chromosomes exchange segments with one another
What is oogenesis?
The process in the ovary that results in the production of female gametes
What is a polar body?
A very small cell produced during oogenesis, containing a nucleus, but very little cytoplasm (figure 7.1.6 pg 144 for diagram)
What is spermatogenesis?
The continuous production of sperm cells in testis (figure 7.1.7 pg 145 for diagram)
What are the three main differences between oogenesis and spermatogenesis?
- Oogenesis produces one egg and a polar body, spermatogenesis produces four sperm
- At birth, an ovary produced contains all the cells that will ever develop into eggs. Sperm is produced continuously
- Sperm are produced continuously, whereas oogenesis has long breaks between stages of division.
What is an independent assortment?
The process by which the paternal and maternal chromosomes of each homologous pair behave independently of the other homologous pairs as they separate in meiosis
