Studied by 1 personthe key roles of cell division
the ability of organisms to produce more of their own kind best distinguishes living things from nonliving matter
reproduction of cells, or cell division
What is the continuity of life based on?
one cell reproduces the entire organism
How do unicellular organisms divide?
development from a fertilized cell, growth, repair
multicellular eukaryotes depend on cell division for what?
genetically identical daughter cells
Most cell division results in what?
meiosis
What is the exception to cell division making genetically identical daughter cells?
meiosis
a special type of division that can produce sperm and egg cells
cellular organization of genetic material
all the DNA in a cell constitutes the cell's genome
chromosomes
What are DNA molecules in a cell packaged into?
a single DNA molecule (prokaryote) or a number of DNA molecules (eukaryote)
What can a genome consist of?
chromatin
unpacked, more functional form of DNA
chromosme
condensed, and neatly coiled up to travel to new cells
somatic cells
nonproductive cells (2n)
gametes
reproductive cells; sperm and egg (n)
n=23
Human # of paired chromosomes
chromosome (labeled)
between # of chromosomes and organism's complexity
What is there no correlation between?
the chromosome of DNA for that new cell
When sister chromatids separate to 2 new nuclei, they become what?
mitosis and cyokinesis
What does Eukaryotic cell division consist of?
mitosis
the division of the genetic material in the nucleus
cyotkinesis
the division of the cytoplasm
non-identical daughter cells that have half as many chromosomes as the parent cell
Meiosis yields what?
mitotic (M) phase, interphase, cytokinesis
What does the cell cycle consist of?
mitotic (M) phase
mitosis and cytokinesis
interphase
cell growth and copying of chromosomes in preparation for cell division
90%
About how much of a cell's life is spent in interphase?
G1, S, G2
What are the 3 stages of interphase?
S phase
DNA is replicated
cleavage furrow
cytokinesis in animal cells
cell plate
cytokinesis in plant cells
prokaryotes (bacteria and archaea)
Who perform binary fission?
binary fission
the chromosome replicates (beginning Athens the origin of replication), and the two daughter chromosomes actively move apart
mitosis
What can prokaryotic cells not undergo?
binary fission
Where do people think mitosis evolved from?
certain protists exhibit types of cell division that seem intermediate between binary fission and mitosis
Why do people think mitosis evolved from binary fission?
molecular control system
The eukaryotic cell is regulated by what?
the usual controls of the cell cycle
What do cancer cells escape?
frequency of cell division
What varies with the type of cell?
G1 checkpoint, G2 checkpoint, M checkpoint
What are the three checkpoints of the cell cycle?
the cell cycle control system
the cell cycle appears to be driven by specific chemical signals present in the cytoplasm
experiments in which mammalian cells at different phases of the cell cycle were fused to form a single cell with 2 nuclei
What is evidence from to support the hypothesis of the cell cycle control system?
cyclins and cyclin dependent kinases (CDKs)
What are the two types of regulatory proteins involved in cell cycle control?
rises and falls
The activity of a CDK __________ and _________ with changes in the concentration of its cyclin partner
maturation promoting factor
What does MPF mean?
MPF
a cyclin-CDK complex that triggers a cell's passage past the G2 checkpoint into the M phase
endogenous
cells can receive signals to divide from within the cell
exogenous
cells can also be signaled to divide by chemical factors outside the cell
growth factors
What are released by certain cells and stimulate other cells to divide?
platelet derived growth factor
What does PDGF mean?
PDGF
made by blood cell fragments called platelets
crowded cells will stop dividing
What happens in density-dependent inhibition?
anchorage dependence
in order to divide, cells must be attached to a substratum
check the growth of cells at an optimal density
What do density dependent inhibition and anchorage dependence do?
neither
What type of regulation do cancer cells have?
cancer cells
may not need a growth factor to grow and divide; they make their own growth factor; they may convey a growth factor's signal without the presence of a growth factor; they may have an abnormal cell cycle control system
transformation
By what process is a normal cell converted to a cancerous cell
benign tumor
abnormal cells remain at the original site
malignant tumor
invade surrounding tissues and can metastasize, exporting cancer cells to other parts of the body, where they may form additional tumors
high energy radiation
What can localized tumors be treated why?
genetics
the scientific study of heredity and variation
heredity
the transmission of traits from one generation to the next
variation
demonstrated by differences in appearance that offspring show from parents and siblings
genes
the units of heredity; made up of segments of DNA
gametes
genes are passed to the next generation via ___________
locus
specific location of a gene on a chromosome
mother
Who do you get your mitochondria from?
asexual reproduction
a single individual passes genes to its offspring without the fusion of gametes
clone
sexual reproduction
2 parents give rise to offspring that have unique combinations of genes inherited from the 2 parents
depends on the way you measure
What is the largest organism in the world?
somatic cell
any other cell than gamete (body cell)
23 pairs
How many pairs of chromosomes do somatic cells in humans have?
homologous chromosomes (homologs)
the 2 chromosomes in each pair
length; genes
chromosomes in a homologs pair are the same _________ and carry ________ controlling the same inherited characteristics
karyotype
an ordered display of the pairs of chromosomes from a cell
X and Y
sex chromosomes
human females
XX
human males
XY (heterologs)
autosomes
Any chromosome that is not a sex chromosome
somatic cells
autosomes are NOT
gametes
sex chromosomes are NOT
cells
Chromosomes are NOT
diploid
2 sets of chromosomes (2n)
haploid
a single set of chromosomes (n)
23
What is the haploid number for humans?
22 autosomes and a single sex chromosome
Each set of 23 consists of:
X
In an unfertilized egg (ovum), the sex chromosome is
X or Y
In a sperm cell, the sex chromosome may be either
fertilization
the union of gametes
zygote
What is a fertilized egg called?
from each parent
A zygote has one set of chromosomes from _________
mitosis
Zygote produces somatic cells by ________ and develops into an adult
meiosis and fertilization (and mitosis)
the 3 main types of sexual life cycles differ in the timing of:
diploid to haploid
Meiosis reduces the number of chromosome sets from:
2 sets of cell divisions
Meiosis consists of:
4 daughter cells
What does meiosis result in?
half
The daughter cells in mitosis have ________ as many chromosomes as the parent cell
meiosis I (reductional division)
homologs pair up and separate resulting in 2 haploid daughter cells with replicated chromosomes
meiosis II (equational division)
sister chromatids separate
comparison of mitosis and meiosis
-mitosis conserves the number of chromosome sets, producing cells that are genetically identical to the parent cell -meiosis reduces the number of chromosomes sets from 2 to 1, producing cells that differ genetically from each other and from the parent cell
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