c ellular r eproduction c ellular r eproduction mitosis & meiosis chapter 9 – mitosis chapter...
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CELLULAR REPRODUCTION
MITOSIS & MEIOSIS
chapter 9 – mitosischapter 10.1 – meiosis
CELL REPRODUCTION=CELL DIVISION
What are the characteristics of living things?
Why is cell division necessary?
How is cell reproduction related to
our other topics of study?
CELL SIZE LIMITATIONSAs cell size increases a cell has difficulty….
o communicatingo obtaining & supplying nutrientso expelling/eliminating wasteo transporting substances - via diffusion, osmosis,
endocytosis
Cells grow until they reach their size limit, then they must stop growing, divide or die.
CELL SIZE LIMITATIONSAs cell size increases… the surface area to volume ratio decreases!!!
The smaller the cell the more efficient it will be!!!
Just as there is a limit to cell size….
there is a limit to the size of living things
In a cell, the DNA is usually present
in a form called CHROMATIN
Before cell division…
the DNA will
replicate (copy)
and
become more compact
forming…
double stranded
CHROMOSOMES
CHROMOSOME STRUCTURE:
A Double-Stranded Chromosome has…
2 identical parts called “sister” chromatids
held together by a centromere (protein disc)
2 TYPES OF EUKARYOTIC CELL DIVISION
MITOSIS makes …. 2 cells body (somatic) cells diploid cells (2n) genetically identical cells maintains chromosome # body cells; somatic cells involves a cell cycle
MEIOSIS makes… 4 cells sex (germ) cells haploid cells (n) genetically different cells reduces chromosome # by ½ sex cells; germ cells; gametes NO cell cycle
2 TYPES OF PROKARYOTIC CELL DIVISION
Prokaryotes are BACTERIA
BINARY FISSION(asexual reproduction)
single, circular chromosome (DNA)
copies itself and the cellsplits into 2 cells
that are genetically identical
.
CONJUGATION(sexual reproduction)
1. Plasmid (loop of DNA) is copied2. Plasmid is exchanged between
bacterial cells (do not need to be the same species)
PLOIDY … refers to the NUMBER OF COMPLETE
SETS OF CHROMOSOMES in a cell
DIPLOID…HAPLOID…POLYPLOID…
DIPLOID CELLS
contain 2 CHROMOSOMES of each homologous pair contain homologous pairs somatic (body) cells = kidney, skin, muscle, bone,… represented 2n (n= # of chromosome pairs)
having 2 sets of chromsomes… 1 set from mother and 1 set from father = 2n
HAPLOID CELLS
contain 1 CHROMOSOME of each homologous pair contain NO homologous pairs sex cells/gametes/germ cells – egg and sperm represented n or 1n (n= # of chromosome
pairs)
having 1 set of chromsomes…
contain 3+ CHROMOSOMES of each homologous pair contain homologous pairs somatic (body) cells represented 3n, 4n, 5n,….
having more than 2 sets of chromosomes chromosome number is greater than 2n
common in plants – wheat, oats, strawberries, lilies,…. exhibit more vigor and size
rare in animals – some fish + amphibians always fatal in humans triploid organism (3n) – has 3 complete sets tetraploid organism (4n) – has 4 complete sets
POLYPLOID CELLS
LET’S PRACTICE – DIPLOID AND HAPLOID
Humans have 46 chromosomes in their body cells….
How many chromosomes do humans have in…. somatic cells? diploid cells? sex cells? haploid cells?
How many chromosome PAIRS do humans have in … somatic cells? diploid cells? sex cells? haploid cells?
Each species has a characteristic chromosome number …
Domestic Cats 38Sheep 54Fruit Fly 8Buffalo 60Corn 20Human 46
Mrs. Dockery’s man crush
THE CELL CYCLE…
3 main phases:Interphase – G1, S,
G2
Mitosis Cytokinesis
Cells don’t go
through the cycle
at the same rate!!!
Cell Division
a repeating series of events in the life of a (somatic)cell
Animation - How the Cell Cycle Works – 1 minutehttp://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_the_cell_cycle_works.html
INTERPHASE the time between divisions the majority of the cell’s lifetime divided into 3 phases….
G1 phase – cell growth, maturation + metabolism
normal cellular activities (photosynthesis, active transport, lipid synthesis,…) S phase – DNA is replicated (copied)
G2 phase – preparation for cell division
SOME CELLS REMAIN IN INTERPHASE THEIR ENTIRE LIFETIME….
These cells enter a state called G0 phase
These cells…. do not copy their DNA do not go through cell division
cells in the central nervous system (brain and spinal cord) do not go through cell division after maturity
BUT..OTHER CELLS MAY GO THROUGH INTERPHASE AND THE CELL CYCLE RAPIDLY AND UNREGULATED
CANCER…
MITOSIS
division of the nucleus (genetic material/DNA) into 2 genetically identical nuclei
4 steps/phases - PMATProphaseMetaphaseAnaphaseTelophase
Animation – Mitosis – 1 minute http://www.youtube.com/watch?v=-G-3BDlnK58
CYTOKINESIS
Immediately follows mitosis division of the cytoplasm into 2 “daughter”
cells (genetically
identical)
Animation - Mitosis and Cytokinesis – 1 minutehttp://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__mitosis_and_cytokinesis.html
PROCESS OVERVIEW
WHY IS CELL DIVISION (BY MITOSIS) NECESSARY?
3 reasons….. GROWTH – adds new cells REPAIR – of damaged tissues and parts MAINTENANCE – cells are always dying
and need to be replaced
HOW IS MITOSIS DIFFERENT AS WE AGE?
occurs very quickly when we are young in adulthood and into old age the process
slows
Live Video – Pig Epithelial Cells Undergoing Mitosis – 1 minutehttp://www.youtube.com/watch?v=P7m3WfzgZdI&feature=player_detailpage
Cells Alive – Animal Cell Mitosis http://www.cellsalive.com/mitosis.htm
Mitosis – Video – 4 minuteshttp://vcell.ndsu.nodak.edu/animations/mitosis/movie-flash.htm
CELL CYCLE REGULATION
NORMAL CELL CYCLE the timing and rate of cell division is important
Red blood cells live about 3-4 months and then must replace themselves, but some white blood cells live for years before replacement
regulated by proteins called CYCLINS
DURATION OF THE CELL CYCLE…VARIES…
depending on the (type) of cell that is dividing….
some eukaryotic cells might complete the cycle in
as few as 8 minutes, others might take up to 1 year
for most normal, animals cells, the cell cycle takes approximately 12-24 hours
ABNORMAL CELL CYCLES…. Cancer Apoptosis Stem Cells
CANCER uncontrolled growth and division of cells cells spend little time in interphase and
therefore undergo mitosis more rapidly cancer is due to A FAILURE TO REGULATE THE CELL CYCLE
CANCER
caused by carcinogens, radiation, genetics
carcinogens - cancer causing agents UV radiation - more exposure the greater the
risk genetics – may predispose you to develop
cancer
the risk of cancer - increases with age
CANCER
Video Segment – Differences between healthy and cancer cells
http://app.discoveryeducation.com/search?Ntt=differences+between+healthy+and+cancer+cells
3D Medical Animation – What is Cancer?
http://www.youtube.com/watch?v=LEpTTolebqo
Animation – Cancer: Unregulated Cell Division
http://www.youtube.com/watch?v=IeUANxFVXKc&feature=related
MASSES OF CELLS ARE CALLED TUMORS
Malignant Tumors (CANCER) invasive destroy nearby tissues life-threatening progressive
Benign Tumors non invasive not life-threatening
APOPTOSIS…programmed cell death
not every cell is destined to survive cells shrink and shrivel in a controlled process
helpful because ….it can help protect organisms from developing cancerous growths
2 examples:fingers and toesleaves
STEM CELLS
2 types:
Embryonic Stem Cells Adult Stem Cells
unspecialized (“blank”)cells; not specialized in structure and function
WHAT IS SPECIAL ABOUT STEM CELLS?
Have the ability to renew themselves develop into many different cell types have potential medical uses because they are UNSPECIALIZED
EMBRYONIC STEM CELLS
taken from an embryo embryo = up to 8th week can differentiate into MANY cell types
ADULT STEM CELLS
taken from a growing human even infants have “adult” stem cells found in bone marrow, believed to be in brain and heart NOT ABLE TO differentiate into all cell types
ADULT STEM CELLS
WHAT ARE SOME POTENTIAL USES OF STEM CELLS?
repair of damaged or degenerating tissues may have medical applications in….
Parkinson's disease, genetic disorders, diseases of degeneration, endocrine abnormalities, congenital disorders, spinal cord injuries and paralysis,…
MEIOSIS…process that….
REDUCES the amount of genetic material (DNA) and
the chromosomes by 1/2
meiosis, like mitosis must befollowed by CYTOKINESIS – in
order for the process of cell division to be complete
MEIOSIS… follows interphase…..a period of cell growth,
DNA replication and preparation for division
produces gametes/sex cells/germ cells…..that are genetically different from each other and will be used in sexual reproduction
does not follow a cell a “cell cycle” as mitosis does
2 nuclear divisions – Meiosis 1 and Meiosis II
OVERVIEW OF
MEIOSIS
MEIOSIS I – THE FIRST NUCLEAR DIVISION4 stages (followed by cytokinesis) –
Prophase 1 = P1Metaphase 1 = M1Anaphase 1 = A1Telophase 1 = T1
SYNAPSIS occurs - the pairing of homologous chromosomes and the formation of tetrads
CROSSING-OVER occurs - the exchange of genetic material between homologous chromosomes
SYNAPSIS AND
CROSSING OVER
MEIOSIS II – THE SECOND NUCLEAR DIVISION
occurs simultaneously in 2 cells
4 stages (followed by cytokinesis) Prophase 2 = P2Metaphase 2 = M2Anaphase 2 = A2Telophase 2 = T2
Phases of Meiosis – Animation http://highered.mcgraw-hill.com/olc/dl/120074/bio19.swf
MEIOSIS IN MALES
CALLED SPERMATOGENESISOCCURS IN THE TESTES
MALE GAMETES ARE…. SPERMATOZOA = SPERM
PRODUCE 4 HAPLOID SPERM (FROM EACH DIPLOID CELL)
MEIOSIS IN FEMALES
CALLED OOGENESISOCCURS IN THE OVARIES
FEMALE GAMETES ARE…. EGG(S) = OVUM (OVA) PRODUCE 1 HAPLOID EGG AND 3 POLAR BODIES (FROM EACH DIPLOID CELL)
COMPARISON - MEIOSIS IN MALES AND FEMALES
Are there other difference in the process of meiosis in males and females? Why?
ASEXUAL SEXUAL REPRODUCTION REPRODUCTION 1 parent 1set of genes no union of
gametes offspring is
genetically identical to the parent
I cell 2 identical cells
2 parents 2 sets of genes fusion of haploid
(1n) gametes offspring is
genetically different from the parents
2 different cells 1 unique zygote
What are the advantages of asexual reproduction? sexual reproduction?
IN SEXUAL REPRODUCTION •two haploid (1n) gametes fuse in a process called FERTILIZATION •their union forms a diploid cell (2n) called a ZYGOTE
IN fertilization …
Haploid (n) + Haploid (n) = Diploid (2n)
EGG + SPERM = ZYGOTE
GENETIC RECOMBINATION
OCCURS DURING CROSSING OVER OF MEIOSIS
allows for variety among organisms
THE MORE VARIETY WITHIN A SPECIES THE MORE LIKELY THAT SPECIES WILL SURVIVE
MITOSIS VS. MEIOSIS
Interactive Table A (open hyperlink)
Interactive Table B (open hyperlink)
Comparison Mitosis and Meiosis – Animation http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/
animation__comparison_of_meiosis_and_mitosis__quiz_2_.html
MITOSIS….LET’S REVIEW….
What occurs in mitosis? Why is this processes used by living things? What types of cells are produced? Are they haploid or diploid? How many cells are produced?
MEIOSIS….LET’S REVIEW….
What occurs in meiosis? Why is this processes used by living things? What types of cells are produced? Are they haploid or diploid? How many cells are produced? What is synapsis? What is crossing over? How does meiosis differ in males and females?