Quiz 4 Flashcards
What is ploidy in terms of cells
refers to the number of sets of chromosomes found in a cell.
Diploid Organisms
Have two sets of chromosomes in their cells; for every chromosome in the nucleus, there is another chromosome that is the same shape and size and carries the same genes.
Homologous chromosomes
Homologous chromosomes are chromosome pairs that are similar in length, gene position, and are joined at the centromere.
Haploid
Only one of each type of chromosome in the nucleus(i.e. there is no homologous partner for each chromosome).
What doe n equal in cell biology
Number of chromosomes
Human gametes are haploid so 2n=23
What is an allele?
One of two or more versions of a gene
Dominant Alleles?
A dominant allele is the allele expressed when more than one allele is present.
Recessive Alleles?
An allele that is masked by a dominant allele when more that one allele is present.
Genotype
An ordered list of cells it carries. (Aa, AA, AaBb).
Phenotype
Is the physical traits expressed by an organism. (Black Hair, Short).
Stages of Meiosis in order
Prophase- Prometaphase 1-Metaphase 1- Anaphase 1- Telophase 1. Interkinesis (Repeats for Meiosis 2)
Stages of Meiosis in order
Prophase- Prometaphase 1-Metaphase 1- Anaphase 1- Telophase 1. (Repeats for Meiosis 2)
Prophase 1
-1st stage of meiosis.
-Chromosomes condense
-Homologous chromosomes pair up by a process called synapsis to form tetrads
Prometaphase 1
2nd stage of meiosis
-Nuclear envelope disintegrates
-Spindles attach to centromeres
Metaphase 1
3rd stage of meiosis
-Tetrads are lined up along the middle of the cell
Anaphase 1
4th stage of meiosis
- Homologous chromosomes are separated and move to opposite poles of the cell by the spindle apparatus.
Telophase 1
5th Stage of meiosis
-Nuclear envelope reforms
-Cytokinesis begins(by a cleavage furrow in animal cells or cell plate in plant cells)
-Each daughter cell contains the haploid number of replicated chromosomes.
Meiosis 2
Separates replicated chromosome into single chromosomes
Meiosis in plants
Meiosis occurs in diploid cells called sporocytes within reproductive organs called sporangia to form haploid spores.
Alternation of generations
Life cycle in plants that have distinct multicellular haploid and diploid stages.
-The diploid generation(Sporophyte) produces haploid spores by meiosis within structures called sporangia.
-Spores undergo meiosis to produce multicellular haploid gametophytes.
-Within the gametophyte reproductive organs will produce gametes(sperm and eggs) by mitosis.
sphorophyte
The diploid generation that produces haploid spores by meiosis within structures called sporangia.
Gametophyte
A reproductive organ that will produce gametes(sperm and eggs) by mitosis.
Chiasma
Chiasmata
-The location where two homologous chromosomes cross over Which is the exchange of genetic material between non-sister chromatids.
