The Nucleus Flashcards
how many membranes does the nucleus have
2
what is the name for the dense fibrillar network inside the nucleus of most cells that provides mechanical support and regulates important cellular events such as DNA replication and cell division
nuclear lamina
what is chromatin composed of
complex of five structural proteins and DNA
when is chromatin movement active
when there is genetic activity such as gene turning on
how many chromosomes does the human cell contain
46
how many autosomes or homogenous pairs of chromosomes do humans have
22
what is the diploid number of somatic cells
2n
what cells have a haploid number of chromosomes
sperm and ovarian cells
what does the lowercase d stand for in mitosis
DNA content
how many base pairs are present in the human genome
more than 3 million DNA base pairs
what are the four DNA bases
adenine
thymine
guanine
cytosine
what are the four phases of the cell cycle
Gap 1 (G1)
synthesis
Gap 2 (G2)
mitosis
what does G0 represent in the cell cycle
phase where the cell exits the cell cycle
at what phase of the cell cycle does the cell divide
mitosis
what is the longest phase of the cell cycle
G1 or growth phase
what happens to the chromosomes during the S phase of the cell cycle
each of the 46 chromosomes are duplicated
during mitosis, one nucleus will become how many nuclei with identical genetic information
2 nuclei
what happens to the nuclear membrane during prophase
it disappears
when do the 2 nuclei of mitosis and cytoplasm split into 2 cells
during cytokinesis
what types of cell undergo meiosis, forming with a haploid number
gametes
what are the two major check points for cell regulation during the cell cycle
between G1 and S
between G2 and M
what is considered the most critical check point in the cell cycle that can result in what is referred to as a mitotic catastrophe that can lead to cell death or tumor development
between G1 and S
what controls the cell cycle checkpoints
cyclin dependent kinases
what protein forms from the cyclin kinase complex, is produced by a tumor suppressor gene, and when defective can lead to retinoblastoma
RB
what protein binds to DNA directly to produce proteins that block the progression of the cell cycle
P35 known as the guardian of the genome
what protein functions to inhibit CDK so it won’t be able to activate DNA replication or mitosis, but does not lead to cancer when defective
P21
defective suppressor genes often lead to what
neoplastic growth
what does the number of mitotic metaphases indicate
the mitotic activity of the cell
what are the 3 major cell population classifications related to cell mitotic activity
static cell populations
stable cell populations
cell renewal populations
what 3 types of cells that are considered static or no longer divide
CNS cells
skeletal muscle cells
cardiac muscle cells
what 4 cell types are considered stable or mitotically active during injury
periosteal and perichondrial cells
smooth muscle cells
endothelial cells of the blood vessels
fibroblasts of the connective tissue
what are the 3 examples of slow renewing cells
smooth muscle cells of most hollow organs
fibroblasts of the uterine wall
epithelial cells of the lens of the eye
what are 3 examples of fast renewing cells
blood cells
epithelial and dermal fibroblasts of the skin
epithelial and sub epithelial fibroblasts of mucosal lining of the GI tract
how many cells are produced in the human body per day
100 billion
what is the frequency of somatic cell mutations
1 every million replications of a cell
what are some common features of neoplastic cells
high mitotic rates
mass forming
failure to activate apoptosis
mutations of future DNA
metastasis
invasion
what are some microscopic features suggestive of malignancy
large, variably sized nuclei
increased cell division
disorganized cell pattern
variation of cell size and shape
loss of normal features
the T antigen of simian virus (SV40) protein that binds to pRb interferes with the specific checkpoints in the cell cycle that have been fond to be involved in which 3 tumors
mesothelioma
osteosarcoma
ependymoma
reserve stem cells may be re-activated into the cell cycle in what 3 circumstances
normal wound healing
radiation
organ regeneration
what happens if the damage to tissue is extensive enough to cause the reserve stem cells to die
no healing or regeneration will occur
what are the three germs layers that can result from an embryonic stem cell
ectoderm
mesoderm
endoderm
what are the 3 major differences between adult stem cells and embryonic stem cells
adult cells have determined type
adult are difficult to culture in-vitro
can only be autologously transplanted
homeostasis is critical in maintaining a balance between what
cell accumulation and cell death
how does cancer impact the balance of homeostasis
it causes cell accumulation
how does ischemic injury impact the balance of homeostasis
it causes cell death
what type of injury may result in necrosis
hypothermia
hypoxia
radiation
low pH
cell trauma
what type of 2 immune cells can destroy cancer transformed cells or cells infected with a viral pathogen
cytotoxic T lymphocytes
natural killer (NK) cells
what factors inhibit apoptosis
growth factors
hormones like androgens and estrogen
neutral amino acids
zinc
interactions with extracellular matrix proteins
several cellular and viral proteins act as a cascade inhibitor
