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mitosis is an...
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:
- most of a cell's life is spent in interphase
- normal functions are carried out
- three stages of interphase: G1, S, G2
- first gap or growth phase
- organelles duplicated
- cells get larger
- synthesis phase
- DNA is copied in this phase
- chromosomes are replicated
- get sister chromatids connected by centromeres
- 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 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 ____
the sister chromatid is connected to the original DNA by a ____
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...
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
the enzyme ______ adds the correct base to the now single strand of DNA
the _____ between sugars and phosphates is made
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...
steps of mitosis
- replicated chromosomes condense
- microtubules form at the poles (ends) of the cell
- the nuclear envelope disintegrates
- replicated chromosomes line up across the equator of the cell
- microtubules attach to the centromeres
- the centromere splits
- microtubules pull sister chromatids apart towards poles
- 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 _______
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...
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...
mutations can be inherited or induced by exposure to...
carcinogens that damage DNA and chromosomes
mutations can be in cell control proteins called...
- proto: before
- onco: cancer
- 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?
- cell division when needed
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...
in suppressors, cells can override the...
- 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 _____
many changes, or hits, to the cancer cell are required for...
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