Download Cell Reproduction

By. Mr. Drake
Review
 1. What does the cell membrane do? What is it made
of?
 2. What organelle has the DNA inside?
 3. What are two methods of reproduction?
 4. Which method is faster?
 5. Why don’t we All look alike?
 6. Can there be mistakes when cells divide?
Asexual vs. Sexual reproduction
 Sexual: 2parents, haploid sex cells
 Sexual: offspring are different, variety
 Sexual: slower than asexual
 Asexual: 1 parent, diploid cells
 Asexual: Offspring are identical
 Asexual: faster, used by many disease-causing
organisms
Chromosomes
 Contain the genetic information found in cells
 Billions of codes that make up individual traits
 Information is stored as DNA strands inside the
chromosomes
 Coiled up and X-shaped
Why are chromosomes in pairs?
 Allows animals to reproduce sexually
 Allows each parent to contribute different
traits=greater diversity
 Humans have 23 pairs of chromosomes.
 Allows sexes to be determined by chromosomes
Chromosomes (Human karyotype)
Sex chromosomes and Autosomes
 Animal cells have two different kinds of chromosomes
 ____________________: determine the sex of an
organism
 “X” or “Y” chromosomes : XX-female XY-male
 ____________: chromosomes that DO NOT
determine sex
 Humans have 44 ______________and 2
___________________
Diploid and Haploid Cells
 Cells with 2 sets of Chromosomes are “diploid”.
 All normal human cells are diploid
 Sex cells are “haploid” or “half”
 Haploid is ½ the Diploid number. (D)=46 (H)=23
 This allows sex cells to bring 2 sets of chromosomes
when they join together
Sex Determination
 Sperm cells ( X or Y) and Egg Cells (X only)
 XX is female
XY is male
 The ____________ determines the offspring’s sex
 Sex Chromosomes are always labeled X or Y, all other
chromosomes have a number….1,2,3 etc.
 Sex cells must go through ____________: cuts
chromosomes by half
Cell Division in Prokaryotes
 _________________: Cell simply divides in half
 The new cells are ALWAYS IDENTICAL.
 Makes millions of new cells a day
Binary Fission
Cell Division in Eukaryotes
 Two phases: Mitosis and cytokinesis
 Chromosomes form: two strands of DNA
 Chromosomes attach at the _______________
Cell Cycle
 _________________: the events of a cell’s life
 ________________: Period of growth between division
 ______: First growth
 ______: DNA copies
 ______: Grows to max size
 ________: Mitosis phase
 Most of the time cells are in interphase, not actively
dividing
 Mitosis usually only takes a few hours
The Cell Cycle
Interphase and Cell division
Mitosis 4 phases (PMAT)
 ___________: Chromosomes
appear, Nucleus breaks
down
 _______________: Very short
cycle— Chromosomes line
up in the middle
 ____________: Chromosomes
split into single strands
“chromatids”, move to
opposite sides
Mitosis continued
 _______________: chromosomes
unwind, two new nuclei appear
 “Cleavage furrow” : split that
occurs down the middle of the
cell
 Leads to 2 identical “daughter cells”
Cytokinesis
 Means “cell splitting”
 Takes a couple of minutes to occur, short time period.
 In Plant cells the cell wall must divide at the “cell
plate”: an extension of the cell wall.
Mitosis pictures (actual cells)
 Prophase:
Metaphase:
 Telophase:
Cytokinesis:
Anaphase:
Steps of mitosis
Mitosis Animation
Meiosis-creates sex cells
 MY-O-SIS
 Cell division that results in the formation of sex cells or
“gametes”
 Sperms cells
undergoing
Meiosis
Meiosis 1
 ______________
 During ______________the chromosomes pair up with
another pair and are known as _______________
 In ______________these pairs line up and then some
parts of the chromosomes will break off and re-attach
 This is called “________________” and is responsible
for new mixtures of DNA and variety of genes.
 “___________________”: new traits that appear due to
crossing over
Crossing over
 In ______________the
chromosomes are pulled
to the ends of the cell
2 new cell are created
and Meiosis 2 begins
Meiosis 2
 __________________
 No copying of DNA
 Begins after the first cell division of meiosis 1
 Meiosis 2: Prophase, Metaphase, Anaphase, and
Telophase (PMAT) occur just as they did in mitosis.
 End result of Meiosis- 4 Haploid cells with either an X
or Y chromosome
Meiosis
Formation of gametes
 ____________: Haploid sex
cells
 Meiosis occurs within
the ovaries and testicles