Studied by 1 person
Looks like no one added any tags here yet for you.
What is the cell theory?
states that all cells come from preexisting cells
What is cell division?
The process by which cells reproduce
All cells contain what?
genes
What are genes?
protein coding sequence in our DNA that makes us, US
When cells divide the genetic information is what?
copied and separated into each daughter cell
DNA (genes) must be what in preparation for this cell division?
packaged tightly
What are chromosomes?
bundle of tightly packed DNA
Where are chromosomes located and why?
the nucleus because thats where DNA is
What are chromosomes composed of?
DNA and protiens
What is the protein in chromosomes called?
histone
What is DNA first coiled around?
histones
After DNA is coiled around a bunch of histones what happens?
the histone complexes are then packed tightly together
The tightly packed bundles of histones and DNA make up what?
chromosomes
Chromosomes are composed 2 identical what?
chromatids
What are chromatids?
identical strands of chromosomes known as sister chromatids
What are these sister chromatids attached to?
a complex protein called centromere
What is the protein that connects the 2 chromatids?
centromere
What is a chromosome composed of?
DNA and proteins (histones)
The number of chromosomes does not correlate to what?
the complexity of an organism
What are homologous chromosomes?
one of two pairs of morphologically similar chromosomes
What is a dipoid?
a cell that contains both chromosomes of a homologous pair
2N refers to
a diploid cell
What is a haploid?
a cell that only has one chromosome of each homologous pair
1N refers to
a haploid cell
What is the cell cycle?
the sequence of five events of cell division: includes 3 phases of interphase, mitosis, and cytokinesis
What is interphase?
the period of cell growth and development that proceeds mitosis
What are the 3 phases of interphase?
G1, S, G2
What is the G1 phase?
Cell growth
What is the S phase?
DNA synthesis
What is G2 phase?
cell undergoes rapid growth to prepare for mitosis, synthesizes necessary enzymes and structures
What is mitosis?
division of the cell nucleus in which the chromosomes of the parent cell divide into two identical sets
What are the phases of mitosis?
prophase, metaphase, anaphase, and telophase
What is early prophase?
breaking down of nucleus and chromosome formation
What is late prophase?
spindle fibers form
What is metaphase?
the line up of chromosomes in the middle of the cell
Where do spindle fibers come from?
centrioles
What are polar fibers?
fibers that go from on centriole to the other centriole
What are kinetochore fibers?
fibers that move the chromosomes to the equator, or center, of the cell
What is meiosis?
the process of nuclear division that reduces the number of chromosomes by half
What is the difference between mitosis and meiosis?
mitosis deals with body cells and meiosis deals with sex cells
What is meiosis I?
first division; homologous chromosomes are separated into separate cells, follows interphase just like mitosis
What are the steps of meiosis I?
Prophase I, Metaphase I, Anaphase I, Telophase I
What is meiosis II?
the second division; chromatids of each chromosome are separated into separate cells
What are the steps of meiosis II?
Prophase II, Metaphase II, Anaphase II, Telophase II
Prophase I?
spindle appears
What is synapis?
Pairing of homologous chromosomes (prophase I)
What is tetrads?
group of two chromosomes, the tetra "four" refers to the amount of chromatids
Metaphase I?
tetrads move to the equator of the cell, they are moved by spindle fibers, and homologous pairs stay together
Anaphase I?
Homologous pairs of chromosomes separate, each chromosome is still composed of 2 chromatids and a centromere
Telephase I?
Cytoplasm divides forming two daughter cells
Meiosis II?
occurs in each cell formed during meiosis I
Prophase II?
chromosomes coil again and new spindle fibers begin to form
Metaphase II?
chromosomes are lined up on the equator of the cell, spindle fibers attach to centromeres
Anaphase II?
centromeres divide, spindle fibers pull each chromatid to the opposite poles
Telephase II?
spindle fibers dissolve, nuclear membrane forms, cells begin to divide (don't fully divide until cytokinesis)
Each new cell created in meiosis is ____________?
haploid
Gametes
sexual reproductive cells
Ootid
egg cell that receives almost all of the cytoplasm
Polar bodies
three other cells that receive very little or no cytoplasm and eventually disintegrate
Each meiotic division results in ______ haploid egg cell.
one
asexual reproduction
the production of offspring from one parent (no union of gametes)
sexual reproduction
production of offspring through meiosis and fusion of gametes
Genetic recombination
results from crossing over and homologous pairs of chromosomes separate independently
Why is sexual reproduction important?
genetic variation
What phase does crossing over occur?
prophase 1 of meiosis
What are the daughter cells of meiosis called?
gametes
Note
Flashcard