quiz 6: mitosis & meiosis

genes

discrete units of hereditary information consisting of duplicated dna

what do single celled organisms divide for

reproduction

what do multicellular organisms divide for

reproductive cells (like gametes) and somatic cells (body cells)

what happens in somatic cells + single-celled organisms

the nucleus divides by mitosis into two daughter nuclei with the same number of chromosomes and genes as the parent cell

examples of single celled organisms that can reproduce asexually

yeast and amoeba

homologous chromosomes

chromosomes that are the same length, have the same centromere position, and contain genes for the same character

chromatin

uncoiled dna and protein

chromosome

threadlike structure of nucleic acids and proteins carrying genetic information in the form of genes

centrosome

region outside of the nucleus that contains a pair of centrioles

centrioles

involved in the development of spindle fibers in cell division

centromere

where spindle fibers attach to

telomeres

dna sequences on the ends of chromosomes that become shorter during every mitotic cycle of somatic cells

what are the first 22 sets of chromosomes called

autosomes

significance of the 23rd set of chromosomes

decides the gender of an individual

what does interphase consist of

G1, S phase, G2

G1 phase

cell grows larger and organelles are copied (cells spend most of their time here performing usual metabolic activities)

S phase

dna is duplicated

G2 phase

cell grows more, makes proteins and organelles, and begins to prepare for mitosis

what happens if a cell is not ready to divide

it will stay in the G0 phase

prophase

spindles begin to form, chromosomes condense, nucleolus disappears, nuclear envelope breaks down

metaphase

chromosomes line up at the metaphase plate

anaphase

microtubules push poles apart and kinetochore microtubules pull chromosomes towards opposite poles

telophase

chromosomes begin to decondense, spindles disappear, nuclear membrane reforms, nucleolus reappears

cytokinesis in animal cells

creates a cleavage furrow + actin ring

cytokinesis in plant cells

cell plate + begins creating cell wall

end product of mitosis

two identical daughter cells

what is uncontrolled mitosis and cell division known as

cancerous cells

what happens if telomeres fail to shorten

cells will continue to divide like in cancer cells

product of meiosis

four different daughter nuclei

difference between mitosis and meiosis in relation to division

mitosis divides once, meiosis divides twice

karyotype

image of an organism’s chromosomes

what separates during meiosis I

homologous pairs

what separates during meiosis II

sister chromatids

synapsis

when homologous chromosomes pair together to form a tetrad

crossing over

exchange in genetic information between homologous chromosomes

independent assortment

when chromosomes randomly align themselves on either side of the equator, creating genetic diversity

what meiosis is the same as mitosis

meiosis II

nondisjunction

when pairs of homologous chromosomes fail to separate during meiosis

disorder examples

down syndrome, williams syndrome, prader-willi syndrome, klinefelter syndrome

what happens in klinefelter syndrome

when an organism has an extra set of sex determining chromosomes

importance of HeLa cells

used to study mitosis due to their rapid and continuous cellular divisions, along with cancer and drug studies