genetics Flashcards
mitosis
process which cell divides into 2 daughter cells which are identical to parent cell
meiosis
fundamental basis of sexual reproduction
prophase
- chromatin condenses, chromosomes become visible
- nuclear envelope begins to dissolve
- spindle fibres begin to form
- centrioles move to opposite sides of cell
metaphase
- nuclear envelope has dissolved completely
- chromosomes move to centre of the cell (equator)
anaphase
- centromeres of sister chromatids split
- spindle fibres guide chromosomes to opposite poles of cell
telophase
- chromosome reach opposite poles of cell
- chromosomes start to unravel
- nuclear envelope reforms around each daughter nucleus
cytokinesis
involves equal division of cytoplasm and organelles among the daughter cells
IN ANIMALS: cleavage furrow (pinching) formed around 2 new daughter cells
IN PLANTS: cell plate forms, separates two new cells
interphase
- cells aren’t dividing
- spend 90% of time
- cells are considered “resting”
meiosis 1
cell division of sex cells
prophase 1
- homologs pair
- crossing over occurs
- chromosomes condense
- spindle forms
- nuclear envelope starts to dissolve
metaphase 1
homologous pairs of chromosomes align along equator of cell
anaphase 1
- homologs separate and move to opposite poles, called segregation
- sister chromatids remain attached at centromeres
telophase 1
- nuclear envelopes reassemble
- spindle disappears
- cytokinesis divides cell into two
prophase 2
- nuclear envelope dissolves
- spindles form
- centrioles move to opposite poles in animal cells
metaphase 2
chromosomes align along equator of cell
anaphase 2
sister chromatids separate and move to opposite poles
telophase 2
- nuclear envelope assembles
- chromosomes de-condense
- spindle disappears
- cytokinesis divides cell into two
what is the difference between normal cell division and cancerous cell division
NORMAL CELLS: grow, divide, and die
- receive signals
CANCEROUS CELLS: don’t die, multiply out of control
- do not receive signals and continue to divide
where does mitosis and meiosis take place
mitosis: in somatic cells, all over body
meiosis: in testes and ovaries
spermatogenesis
- occurs in testes
- two divisions produce 4 spermatids
- spermatids mature into sperm
- begins at puberty for males
oogenesis
- occurs in ovaries
- two divisions produce 3 polar bodies that die and 1 egg
- polar bodies die bc of uneven division of cytoplasm
- immature egg called oocyte
- begins at puberty, one oocyte matures into an ovum every 28 days
abnormal meiosis
types of errors that can occur to chromosomes
- changes in chromosome structure + number
these mutations affect the structure of a chromosome:
1. deletion
2. duplication
3. inversion
4. translocation
non-disjunction
chromosomes fail to separate during meiosis
- occurs in anaphase 1 or 2 of meiosis
TWO WAYS IT OCCURS:
monosomy: condition where single chromosome is in place of a homologous pair
trisomy: 3 homologous chromosomes are in place of a homologous pair
disorders
trisomy 21: down syndrome
trisomy 18: edward syndrome
trisomy 13: patau
gender:
XXY: klinefelter
XYY: jacobs
XXX: triple X
XO: turner
