1.6 cell division Flashcards
where does each chromosome + its partner come from?
one from each parent
how many pairs of chromosomes do humans have?
23
which cells are diploid and which are haploid?
body (somatic) cells = diploid
sex cells (gametes (sperm, egg)) = haploid
cell cycle
a series of events that a cell goes through. includes growth, DNA replication, cell division, and the creation of two genetically identical daughter cells
2 phases of the cell cycle
interphase and mitotic phase
interphase
parts of the cell cycle where the cell is not dividing. the majority of the time the cell is in this phase
events that happen during interphase
metabolic reactions, protein synthesis, organelles increase in number (ex: centrioles replicate), DNA replication
how long are human chromosomes?
17mm to 80mm, must be supercoiled to fit in nucleus
which protein helps DNA coil itself in eukaryotes?
histones
what happens in prophase? (4 parts)
- DNA supercoils and becomes condense
- nuclear membrane breaks down and disappears
- 2 centrioles move to the poles of the cell
- microtubule spindle fibers connect to the centrioles
what happens in metaphase? (2 parts)
- microtubules extend from the centrioles and attach to the centromere of the sister chromatids
- chromosomes are lined up along the center of the cell
what happens in anaphase? (2 parts)
- sister chromatids are separated and travel towards poles (microtubules contract)
- centromere divides
what happens in telophase? (2 parts)
- chromosomes arrive at the poles + decondense / uncoil
- nuclear membrane reforms
mitosis
division of the nucleus
cytokinesis
division of cytoplasm and cell, occurs at the same time as telophase
cytokinesis in animal cells (3 parts)
- a ring of contractile proteins (actin microfilaments) pull the cell membrane together at the center
- this pinching creates a cleavage furrow
- cell pinches into 2 new daughter cells
cytokinesis in plan cells (6 parts)
- vesicles (from golgi) line up along center of cell
- fuse together to form tubular structures
- merge + form the cell plate
- cell plate becomes 2 new plasma membranes, 2 daughter cells are now present
- cellulose is secreted to form a cell wall b/w daughter cells
- pectin is also secreted b/w cells
cyclin
a family of proteins that control the progression of the cell cycle. diff cyclins control diff phases
what do cyclins bind to?
cyclin-dependent kinases (cdk)
what do cyclin-dependent kinases do?
activate other proteins/enzymes via phosphorylation
what happens when cell division goes wrong?
tumors: masses that result from the abnormal new growth of cells/tissues
what types of tumors are there (2)?
benign (non-cancerous), malignant (cancerous)
metastasis
the spreading of malignant tumors in one part of the body (primary tumor) to other parts, resulting in new tumor growth (secondary tumor)
mutation
a change in an organisms’s genetic code
mutagen
agents that can lead to mutation
4 examples of mutagens
chemicals (carcinogens), high-energy radiation (X-rays), short wave radiation (UV light), some viruses
oncogene
control the cell cycle and cell growth, can be cancerous if a mutation occurs in an oncogene
kinetochore
large protein assemblies that connect chromosomes to microtubules
A cell that is dividing too rapidly may have lost its ability to enter which part of the cell cycle?
G1 phase
how to calculate mitotic index
the number of cells in mitosis (prophase, metaphase, anaphase, and telophase) must be divided by the total number of cells visible
Which cyclin increases to trigger the beginning of mitosis?
Cyclin-B
Name the phase of the cell cycle when DNA duplicates?
S phase
Which cyclin increases to trigger the beginning of mitosis?
Cyclin B
