-
mitosis is an...
asexual division
-
mitosis is part of the cell cycle, which is what?
the life cycle of the cell
-
mitosis makes new cells that are...
exactly the same as the original cells
-
for cells that divide by mitosis, there are 3 steps in the cell cycle:
- interphase
- mitosis
- cytokinesis
-
interphase
- most of a cell's life is spent in interphase
- normal functions are carried out
- three stages of interphase: G1, S, G2
-
G1 (Interphase)
- first gap or growth phase
- organelles duplicated
- cells get larger
-
S (Interphase)
- synthesis phase
- DNA is copied in this phase
- chromosomes are replicated
- get sister chromatids connected by centromeres
-
G2 (Interphase)
- second gap phase
- synthesis of proteins necessary for mitosis
-
the purpose of mitosis is to separate the sister chromatids so that...
each new cell has a complete set of chromosomes
-
before dividing, a copy of ___ must first be made
DNA
-
DNA is located in the nucleus and carries genes, which are...
instructions for building the proteins that cells require
-
DNA is organized into structures called chromosomes which...
can carry hundreds of genes along their length
-
the number of genes in each cell depends on...
the organism; humans have 46
-
DNA starts out in...
a string-like, uncondensed form
-
before cell division, DNA is condensed into...
short, linear chromosomes
-
when a chromosome is replicated during cell division...
the copy carries the same genes
-
each chromosome is copied and the copy is called a ____
sister chromatid
-
the sister chromatid is connected to the original DNA by a ____
centromere
-
DNA is a double stranded molecule made of...
two single strands of nucleotides that are bonded together
-
the DNA molecule looks a lot like...
a twisted rope ladder
-
the "handrails" of the molecule are called the backbone which is made of...
sugars and phosphates
-
the ____ and ____ parts of the nucleotides are connected
sugar and phosphate
-
the "rungs" of the molecule are the bases:
- A (adenine)
- T (thymine)
- G (guanine)
- C (cytosine)
-
the bases across the "ladder" are connected in a specific way
- A always bonds with T
- C always bonds with G
-
the connection between the molecules in the ladder are...
hydrogen bonds
-
James Watson and Frances Crick
- determined the structure of the DNA molecule
- published in Nature in 1953
-
DNA molecule separates at _____ that hold bases together
hydrogen bonds
-
the enzyme ______ adds the correct base to the now single strand of DNA
DNA polymerase
-
the _____ between sugars and phosphates is made
covalent bond
-
DNA replication results in...
two identical DNA molecules
-
each new DNA molecule is...
half new and half from the old molecule
-
when an entire chromosome is copied, the two sister chromatids are connected...
at the centromere
-
after DNA replication, the cell is ready...
to divide
-
steps of mitosis
- prophase
- metaphase
- anaphase
- telophase
-
prophase
- replicated chromosomes condense
- microtubules form at the poles (ends) of the cell
- the nuclear envelope disintegrates
-
metaphase
- replicated chromosomes line up across the equator of the cell
- microtubules attach to the centromeres
-
anaphase
- the centromere splits
- microtubules pull sister chromatids apart towards poles
-
telophase
- nuclear envelopes reform around chromosomes
- chromosomes revert to uncondensed form
-
what is cytokinesis?
the cell itself divides in half creating two identical daughter cells
-
for plant cells, rigid cell wall prevents...
cell membrane from pinching in
-
prophase, metaphase, anapase, and telophase are similar in plant cells to _______
animal cells
-
during cytokinesis, a ____ from vesicles made of _________ and proteins that will become a new cell wall
cell plate; cellulose
-
animal cells produce a band of filaments that...
divide the cell in half
-
after cytokinesis, cell reenters the G1 phase interphase and...
repeat the cell cycle if the conditions are right
-
cells that go through the cell cycle in unfavorable conditions can lead to...
tumors
-
checkpoints
cell determines if cell is ready to enter next part of cell cycle
-
when the proteins that regulate the cell cycle don't work...
- the cell divides uncontrollably
- results in a tumor
-
mutations in the DNA can produce...
nonfunctioning proteins
-
mutations can be inherited or induced by exposure to...
carcinogens that damage DNA and chromosomes
-
mutations can be in cell control proteins called...
- proto-oncogenes
- proto: before
- onco: cancer
-
proto-oncogenes
- normal genes on many different chromosomes
- regulate cell division
- when mutated, they become oncogenes
- many organisms have proto-oncogenes
- many organisms can develop cancer
-
proto oncogenes carry instructions for what building growth factors?
- stimulate
- cell division when needed
-
oncogenes overstimulate...
cell division
-
receptor proteins on the surface of a cell...
recognize and bind to a specific chemical signal
-
tumor suppressors are genes that...
carry instructions for producing proteins that stop cell division if necessary
-
suppressors are backup in case...
protooncogenes are mutated
-
suppressors can be...
mutated
-
in suppressors, cells can override the...
checkpoints
-
angiogenesis
- growth of blood cells caused by secretions from cancer cells
- cancer cells can divide more
- tumors develop, sometimes filling entire organs
-
contact inhibition in normal cells
prevents them from dividing all the time, which would force the new cells to pile up on each other
-
anchorage dependence in normal cells...
keeps the cells in place
-
cancer cells divide too quickly and can...
leave the original site and enter the blood, lymph, or tissues
-
most cells divide a set number (60-70) of times, then they stop dividing, which...
limits benign tumors to small sizes
-
cancer cells can divide indefinitely, as they are ____ through the manipulation of the enzyme _____
immortal; telomerase
-
many changes, or hits, to the cancer cell are required for...
malignancy
-
multiple hit model describes...
the process of cancer development
-
mutations can be inherited and/or can stem from...
- environmental exposures
- knowledge of cancer risk factors is important
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