Chapter 6- Chromosomes And Meiosis Flashcards
What are somatic cells? What are germ cells?
Cells that make up your body cells, tissues. Can copy themselves.
Germ-cells in your reproductive organs that develop into gametes
How many chromosomes does a human have? How many pairs of chromosomes does a human have? What is a pair of chromosomes called?
46 chromosomes in 23 homologous pairs.
What are autosomes? What is the 23rd homologous pair of chromosomes?
Chromosomes that contain genes for characteristics not directly related to the sex of the organism (1-22). The 23rd pair is the sex chromosome.
What is the sex chromosome for a female? Male?
Female-XX
Male-XY
What is fertilization?
The actual fusion of an egg and sperm cell into one nucleus
What are diploid cells and what are examples of them?
Diploid cells are Ellis that have 2 copies of each chromosome, one from mother and father. Ex. Muscle cells, skin cells
What are haploid cells and what are examples of them?
Haploid cells only have one copy of each chromosome. Ex. Gametes, sperm and egg
Which parent’s gametes determines the sex of the child?
The male sperm either carries an X or a Y chromosome for the mother who has an X.
What is meiosis? What is the result of meiosis?
Meiosis divides diploid cells into haploid cells. Meiosis produces gametes. Meiosis results in 4 haploid cells from 1 diploid cell.
What occurs in prophase 1 and 2?
- The nuclear membrane breaks down.
- Centrosomes and centrioles move to opposite sides of the cell
- Homologous chromosomes pair up
What happens in metaphase 1 and 2?
- Homologous chromosomes randomly line up along the cell equator
What happens in Anaphase 1? Anaphase 2?
A1-The homologous pairs separate and move to opposite sides of the cell
A2-the sister chromatids separate and move to opposite sides of the cell
What happens in telophase 2? What is the result?
- A nuclear membrane forms around each set of chromosomes
2. RESULT–4 haploid cells that are genetically unique
What are traits?
Inherited characteristics
What is a purebred? What is a cross?
A type of organism whose ancestors are genetically uniform
Cross-the mating of two organisms
What were Mendel’s 3 conclusions?
- Traits are inherited as individual units
- Organisms inherent 2 copies of each gene, one from each parent
- Organisms can only donate one copy of each gene in their gametes
What is a gene? What is a locus for a gene?
A piece of DNA that provides a set of instructions to a cell to make a certain protein.
Locus-each gene’s specific position on a pair of homologous chromosomes
What is an allele? What is homozygous? Heterozygous?
One part of a genotype given from a parent.
Homo-two of the same alleles at a specific locus (AA, aa)
Heterosexual-two different alleles at a specific locus (Aa)
What is a genotype? What is an example of a phenotype?
The genetic makeup of a specific set of genes. (The AA as being one)
Phenotype-purple flower pedals
What is a testcross?
A cross between an organism with an unknown genotype and a recessive phenotype. The heterozygous genotype is used for the unknown (ex. Aa x aa)
What is the law of independent assortment?
Allele pairs separate independently of each other during gamete formation
What are the two causes for genetic variation? How many combinations of homologous pairs are there after meiosis? How many after fertilization?
- Independent assortment
- Random fertilization of gametes
After meiosis- 8 million combos
After fertilization-70 trillion combos
What is genetic linkage?
Genes located close together on a certain chromosome tend to be inherited together.
Homologous chromosomes are pairs of chromosomes containing genes that code for?
The same traits
What is a haploid cell and an example? Diploid cell and an example?
Haploid-has only one set of chromosomes. Ex. A germ cell
Diploid-has both sets of chromosomes from each parent. Ex. A skin cell
When does crossing over occur?
During prophase 1
When does Mendel’s law of segregation state?
The two alleles for a trait SEGREGATE independently when gametes are formed
What is the difference between Mendel’s experiments and those done by earlier researchers?
Mendel expressed the results of his experiments in terms of numbers
