cell reproduction review of biomolecules dna cell reproduction mitosis nuclear/cell division +...
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CELL REPRODUCTION • Review of Biomolecules• DNA• Cell Reproduction
Mitosis Nuclear/Cell Division + Cytokinesis
Meiosis Sexual Reproduction; ‘2n’ to ‘n’
Biomolecules ??
• Proteins• Amino Acids (20)
• Nucleic Acids• Nucleotides• DNA/RNA
• Carbohydrates• Monosaccharides• Sugars
• Lipids• Fatty Acids
Structure of DNA• Stores Genetic Information• A Double helix ladder of connected nucleotides forming a
sugar-phosphate “backbone” and nitrogen base “steps”• Each nucleotide of DNA consists of:
A sugar “deoxyribose”A phosphate A nitrogenous base:
Adenine ThymineCytosine Guanine
DNA STRUCTURE
*HandoutGene = allele = traits 1 from each parent 2m/6.5’ of DNA/cell
Clip on DNA…compacts tightly• Visualizing Cell Processes• DNA structure• Chromosome Condensation
Cell Reproduction
Introduction to chromosomes
(the cells’ library of genetic material)
Study Two Processes: Mitosis & Meiosis
1. Mitosis -cell division of Body (Somatic) cells. ‘2n’ diploid = complete set #?
2. Meiosis- division of sex cells (Gametes) egg, sperm ‘n’ Haploid = ? In humans
Mitosis: everywhere ; Meiosis: reproductive organs only
P/S: Reasons for Cell Reproduction
1. Replace/Maintenance (skin, blood, digestive)
2. Growth
3. Repair (scrape knee, break bone)
4. Reproduction of species: pass down genetic material for continuation of the species (mutations/adaptions/natural selection)
•ChromatinPartially “unraveled”
Chromosomes (95%)
•Chromosome A ‘single’ structure …
DNA*nucleosome proteins
•Chromatid 2 identical copies of a
chromosome (attached)
“sister chromatids”
All refer to the cells’
DNA content at different stages
Homologous Chromosomes
From Dad From Mom
eye color locus(ex-’b’ blue)
eye color locus (ex-’B’ brown)
hair color locus
hair color locus
CENTROMERE
ALLELE FOR EYE COLOR
_____ _____Sister Chromatids(identical) *Nonsister
Unreplicated Chromosome, when copied = 2 chromatidsHeld together by a centromere- form a replicated chromosomeHomologous chromosomes: 23 PAIRS (From mother/father…similar in size/shape and centromere position
Chromosomes are counted on karyotypes
Karyotype
-Human Somatic Cell: #?• 46 chromosomes
• 23 pairs ….’body’?
• 44 autosomes• 22 pairs ….’sex’?
• 2 sex chromosomes• 1 pair ….M/F?
• XX = female• XY = male
Allele: Different forms of a gene (Blue, brown eyes)
TWO TYPES OF CELLS:SOMATIC and GAMETES
SOMATIC: (Body Cells)
(Body cells: skin/muscle/liver/bone/brain/blood)
Diploid Cells (2n): The # of chromosomes in a somatic cell 2n = ? in humans…varies/species
GAMETES: (Sex Cells)
(Sex cells = Gametes = Humans?) 23 Sperm + 23 Egg = 46 Zygote (The fertilized egg)
Plants?
Haploid Cells (n): The # of chromosomes in a sex cell n = 23 in humans (half a complete set)
46
The Making of New Prokaryotes: Binary Fission (asexual) (see notepage)
• DNA attached to the inner membrane
• DNA (plasmid) copies• New cell wall forms• Then splits in two, creating two bacteria with IDENTICAL DNA. replicates in ~20minutes
EukaryoticCell Cycle: Repeating
set of events that
make up the life of a
cellInterphase +
PMAT (Mitosis)+ Cytokinesis
Cytokinesis:
Cytoplasm Divides
G o P
hase
Mitosis + Cytokinesis
Cell Cycle: An Interactive AnimationCycle of
growth and division.
Interphase-(G1 + S + G2) time between cell divisions (cell growth)
is most active.TIME TO COMPLETE?
Plant Cell: 10-30 HrsAnimal Cell: 18-24 Hrs
PROPHASE• Chromosomes Condense• The nuclear envelope disappears
(dotted line = breakdown or forming• The centrioles move to opposite poled• The spindle starts to form, growing
out of the centrioles towards the
chromosomes
Metaphase• Chromosomes line
up on the equator of the cell• Spindle fibers are attached
to the centromeres
Human Cell- how many
Will be lined across?
Anaphase• Centromeres divide• Spindle fibers contract
and the chromosomes are
pulled to opposite poles
Telophase• In telophase the cell actually divides• The chromosomes are at the poles of the spindle• The spindle disintegrates• The nuclear envelope reforms around the two sets of
chromosomes• Set for cytokinesis to occur
Cytokinesis• Division of cytoplasm and its contents• Results in 2 daughter cells• Animal cells- Furrow formed
by microfilaments- pinches
plasma in half “cleavage furrow”• Plant cells- a new cell wall
made of cellulose forms
between the 2 new nuclei
Summary of Mitosis
Plant Cell Cytokinesis
MITOSIS
• Mitosis + Cytokinesis = 2 new cells with the same genetic information as the original cell
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