zo2 Flashcards
DNA is tightly coiled around proteins called ___
histones
Duplicated chromosomes are called ____& are held together by the ___
chromatids
centromere
First 22 pairs of chromosomes are called
Last pair are the ___ chromosomes
XX ____or XY _____
autosomes
sex
XX female or XY male
_____involves a single cell dividing to make 2 new, identical daughter cells
Ex: Asexual reproduction
Asexual reproduction
____reproduction involves two cells (egg & sperm) joining to make a new cell (zygote) that is NOT identical to the original cells
Ex: Meiosis
Sexual
Prokaryotes such as bacteria divide into 2 identical cells by the process of
binary fission
FIVE PHASES OF THE CELL CYCLE
G1 - primary growth phase
S – synthesis; DNA replicated
G2 - secondary growth phase
collectively these 3 stages are called interphase
M - mitosis
C - cytokinesis
G1 - primary growth phase
S – synthesis; DNA replicated
G2 - secondary growth phase
collectively these 3 stages are called interphase
M - mitosis
C - cytokinesis
What phase in Cell Cycle?
1st growth stage after cell division
Cells mature by making more cytoplasm & organelles
Cell carries on its normal metabolic activities
Interphase - G1 Stage
What phase in Cell Cycle?
2nd Growth Stage
Occurs after DNA has been copied
All cell structures needed for division are made (e.g. centrioles)
Both organelles & proteins are synthesized
Interphase – G2 Stage
What phase in Cell Cycle?
Synthesis stage
DNA is copied or replicated
Interphase – S Stage
Division of the nucleus
Also called karyokinesis
Only occurs in eukaryotes
Has four stages
Doesn’t occur in some cells such as brain cells
Mitosis
FOUR MITOTIC STAGES?
1.
2.
3.
4.
Prophase
Metaphase
Anaphase
Telophase
What mitotic phase?
Chromatin in nucleus condenses to form visible chromosomes
Mitotic spindle forms from fibers in cytoskeleton or centrioles (animal)
Early Prophase
What mitotic phase?
Nuclear membrane & nucleolus are broken down (disintegrate)
Chromosomes continue condensing & are clearly visible
Spindle fibers called kinetochores attach to the centromere of each chromosome
Spindle finishes forming between the poles of the cell
Late Prophase
What mitotic phase?
Occurs rapidly
Sister chromatids are pulled apart to opposite poles of the cell by kinetochore fibers
Centromeres divide into two
Anaphase
What mitotic phase?
Chromosomes, attached to the kinetochore fibers, move to the center of the cell
Chromosomes are now lined up at the equator
Metaphase
What mitotic phase?
Sister chromatids at opposite poles
Spindle disassembles
Nuclear envelope forms around each set of sister chromatids
Nucleolus reappears
CYTOKINESIS occurs
Chromosomes reappear as chromatin
Telophase
Means division of the cytoplasm
Division of cell into two, identical halves called daughter cells
In plant cells, cell plate forms at the equator to divide cell
In animal cells, cleavage furrow forms to split cell
Cytokinesis
are special proteins that increase the chance that a normal cell develops into a tumor cell
Oncogenes
_____ is the process of duplicating a chromosome
Occurs prior to division
Replicated copies are called sister _____
Held together at____
Replication
chromatids
centromere
produces gametes with
one copy of each chromosome and thus one copy of each gene.
Meiosis II
Wnat process?
Occurs in the testes
Two divisions produce 4 spermatids
Spermatids mature into sperm
Men produce about 250,000,000 sperm per day
Spermatogenesis
Wnat process?
Occurs in the ovaries
Two divisions produce 3 polar bodies that die and 1 egg
Polar bodies die because of unequal division of cytoplasm
Immature egg called oocyte
Starting at puberty, one oocyte matures into an ovum (egg) every 28 days
Oogenesis
