cell division and reproduction Flashcards
what is a somatic cell ?
a plant or animal cell that forms the body of the organism; excludes reproductive cells (sperm and egg)
what are the 3 functions of reproduction ?
- growth of organism
- repair of tissues and organs that have been damaged
- replace dying or dead cells
how long does the cell cycle take ?
12 to 24 hours
where are the shortest living cells in the body found ?
the lining of the stomach
where are the longest living cells in the body found ?
nerve cells i.e. spinal chord, brain
when do our brain cells stop growing ?
they stop growing when we’re about 20 and die as we age
what are the 6 stages of the cell cycle ?
- interphase
- prophase
- metaphase
- anaphase
- telophase
- cytokinesis
what happens during the stage of interphase ? how much of the cell life is spent in this stage ?
- 90-95 % of the cell life is spent in interphase
- the cell does everything except replicate
- it is called the resting stage
- the DNA duplicates at the end of interphase
what happens during prophase ?
- nuclear membrane disappears
- chromatins shorten and thicken into visible chromosomes
what happens during metaphase ?
- the chromosomes line up on the equator of the cell, the middle of the cell
what happens during anaphase ?
- chromosomes split through the centromere into two identical single strands
- migrate to opposite sides, poles
what happens during telophase ?
- nuclear membrane reappears
- DNA/chromosomes turn back into chromatin
what happens during cytokinesis ?
- dividing cytoplasm with all organelles
- each cell gets equal amounts of organelles
- animal cell = cleavage furrow, plant cell = cell plate
how many pairs of chromosomes are in the nucleus of a cell ?
there are 23 pairs (46) chromosomes
chromatid =
1 half of a double-stranded chromosome
chromatin =
strand
what are homologous chromosomes ?
pairs of chromosomes that appear similar, in terms of their length, centromere location and banding pattern when stained with certain dyes
are homologous pairs identical ?
homologous pairs are not identical; they are alleles
what is an allele ? what are alleles represented by ?
- different version/ form of the same gene
- alleles are represented by letters
what are genes ?
sections of DNA that contain genetic information for the inheritance of specific traits
what are nucleotides and what are they made of ?
made of nitrogen base, sugar and phosphate
they are the smallest unit of measure
what is a karyotype ?
a photograph of pairs of homologous chromosomes in a cell, the set of chromosomes of an individual
how is a karyotype done ?
- white blood cells are stopped during metaphase and a picture is taken
- the chromosomes are shortened and thickened during metaphase, which makes them clearly visible
- white blood cells are big and red blood cells do not have a nucleus
- the sample is stained, which produced a banding pattern on the chromosomes
- chromosomes are taken out and matching pairs are found
- they are aligned according to length, centromere location and banding pattern
what is a gamete ?
a male or female reproductive cell (sex cell)
what is a zygote ?
a cell formed by the fusion of two gametes
what is fertilization ?
in humans, the joining of male and female haploid gametes, egg and sperm meeting to create a zygote
what is a haploid cell ?
a cell that contains half the number of chromosomes as the parent cell
what is a diploid cell ?
a cell that contains pairs of homologous chromosomes
what is meiosis ?
the cellular process that produces cells containing half the number of chromosomes as the parent cell, genetic diversity is the goal