Lab 7 Flashcards
what do nuclei of eukaryotic organisms contain
clusters of genes
genes
units of heredity information consisting of duplicated DNA
what is the purpose of structural proteins in chromosomes
organize the DNA and participate in DNA folding and condensation
what happens to chromosomes when cells divide
they are duplicated and then passed on to the daughter cells
how do single celled organisms reproduce
divide for reproduction
what do multicellular organisms have to allow for reproduction
reproductive cells
-egg
- sperm
somatic cells
divide for growth and development or replacement
what process do somatic cells and single celled organisms go through
the nucleus divides by mitosis into 2 daughter cells
through asexual reproduction and mitosis what is produced
a genetically identical clone
what process do multicellular organisms go through
sexual reproduction and meiosis
meiosis
certain cells in ovaries or testes divide twice, but the chromosomes only replicate once
what is the result in meiosis
four daughter nuclei with half the number of chromosomes
what is one of the major differences between mitosis and meiosis
meiosis contributes to genetic variation that is important in sexual reproduction, while mitosis creates identical clones of a cell
what happens in both mitosis and meiosis
cytokinesis
cytokinesis
cytoplasm divides after nuclear division
cell cycle
events that take place from the beginning of one cell division to the next
- 2 phases
what are the two major phases of the cell cycle
interphase and mitotic (M) phase
M phase
nucleus divides in mitosis and the cytoplasm divides in cytokinesis
diploid cell
2n
- four chromosomes
- two pairs of homologous chromosomes
homologous chromosomes
- same length
- same centromere position
- contain genes for the same characters
centrosome
granular region that contains a pair of centrioles
- organizing center for microtubules in animal cells
sister chromatid
each strand of duplicated chromosomes
- identical to each other
- held together most tightly at the centromere
what are the 5 stages of mitosis
prophase
prometaphase
metaphase
anaphase
telophase
spindle
fibrous round structure tapering toward each end centrioles
blastulas
early embryonic stage
- cells will be dividing at any given time
what forms a diploid zygote in meiosis
fused nuclei
what does a zygote develop into
rounded structure called perithecium
- contains structures called asci
non-recombinants
produced from cells in which no crossing over occurred
recombinants
asci result from cells in which crossing over has occurred
- measure of how often crossing over occurs
map unit
cannot see genes, but due to relationship between distance and recombinant frequency, can describe distance of gene from centromere
how is map distance calculated
taking % recombinant frequency for the asci and divide by 2
- % recombinants=map units
what counts as one chromosome
when two sister chromatids still stick together
when are haploid cells obtained in meiosis
at the end meiosis I
