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CELL DIVISION and DNA. Cell Reproduction. Differentiation. All the cells in your body have the same DNA The fertilized egg (zygote) that made you divided many times - PowerPoint PPT Presentation
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DifferentiationDifferentiationAll the cells in your body have the All the cells in your body have the
same DNAsame DNAThe fertilized egg (zygote) that made The fertilized egg (zygote) that made
you divided many timesyou divided many timesCell differentiation-Cell differentiation- starting stem cells starting stem cells
changed into all the different cell types changed into all the different cell types you have by turning on certain genes in you have by turning on certain genes in your DNAyour DNA
Stem cells-Stem cells- the cells in early the cells in early development that have the potential to development that have the potential to become any type of cellbecome any type of cell
Differentiation VideoDifferentiation Video
STEM CELLAll types of cells stem from these
cells early indevelopment of
Babies.
3 Types of Cell Division3 Types of Cell Division 1. 1. Binary fissionBinary fission -cell division in -cell division in
prokaryotesprokaryotes 2. 2. Cell Cycle (with Mitosis)Cell Cycle (with Mitosis) -cell -cell
division in eukaryotesdivision in eukaryotes 3. 3. MeiosisMeiosis—cell division to form sex —cell division to form sex
cells (egg and sperm)cells (egg and sperm)
Prokaryotes Cell DivisionProkaryotes Cell Division Unicellular so divide Unicellular so divide
by binary fission by binary fission Circular DNACircular DNAResults in two cells Results in two cells
genetically the samegenetically the sameWhat has to take What has to take
place before ANY place before ANY cells divide?cells divide?
Reasons for Eukaryote Cell Reasons for Eukaryote Cell DivisionDivision
Cell division in multicellular Cell division in multicellular organisms results in:organisms results in:– GrowthGrowth– Repair or replacement of somatic (body) Repair or replacement of somatic (body)
cells.cells.– Control of size so nutrients can get in Control of size so nutrients can get in
and waste can get out in a timely and waste can get out in a timely fashionfashion
Reasons for Eukaryote Cell Reasons for Eukaryote Cell DivisionDivision
Some cells die quickly and need Some cells die quickly and need to be replaced a lot (skin cells)to be replaced a lot (skin cells)
Some cells never get replaced Some cells never get replaced (nerve cells)(nerve cells)
Some organisms can regenerate Some organisms can regenerate whole body partswhole body parts
Eukaryotic cells goes Eukaryotic cells goes through a series of phases through a series of phases throughout their lifethroughout their life
The The cell cyclecell cycle-all events -all events between one cell division between one cell division and the nextand the next– It is **ONE REPLICATION & It is **ONE REPLICATION &
ONE DIVISIONONE DIVISION– Result? 2 daughter cells Result? 2 daughter cells
genetically exact to the genetically exact to the parent cell they came parent cell they came fromfrom
2 basic parts of the cell 2 basic parts of the cell cycle: cycle: -1.Interphase--1.Interphase- the the
longest part of cell longest part of cell cycle composed of cycle composed of G1, S, G2 stagesG1, S, G2 stages
--2.M= Mitosis2.M= Mitosis = = Nuclear divisionNuclear division
G1 phase-G1 phase- 1 1stst step of Interphase in the cell step of Interphase in the cell cyclecycle– G1 (G=gap)G1 (G=gap)– Cell going through intense growth using lots of Cell going through intense growth using lots of
food and energyfood and energy– DNA at this point is unwound and called DNA at this point is unwound and called
chromatinchromatin
S phaseS phase -2 -2ndnd step of Interphase in the cell step of Interphase in the cell cyclecycle– S=Synthesis phaseS=Synthesis phase– All DNA replicated during this phase so new All DNA replicated during this phase so new
DNA being synthesizedDNA being synthesized cell has double the cell has double the genetic material genetic material
– Sister chromatid-Sister chromatid- one of two identical parts of one of two identical parts of a replicated chromosomea replicated chromosome
G2 phase-G2 phase- 3 3rdrd step of Interphase in the cell step of Interphase in the cell cyclecycle– G=gapG=gap– Cell grows some moreCell grows some more– Extra organelles are being madeExtra organelles are being made
M phase-M phase- part of cell cycle after Interphase (G1, S, and G2) in part of cell cycle after Interphase (G1, S, and G2) in which nuclear division occurswhich nuclear division occurs– M=M=MitosisMitosis = Nuclear division = Nuclear division– MITOSIS IS MITOSIS IS ONLYONLY THE DIVISION OF THE NUCLEUS DURING THE CELL CYCLE!!! THE DIVISION OF THE NUCLEUS DURING THE CELL CYCLE!!!– There are four mitotic steps:There are four mitotic steps:
ProphaseProphase MetaphaseMetaphase AnaphaseAnaphase TelophaseTelophase
Prophase of MitosisProphase of Mitosis DNA coils up into DNA coils up into
visible visible chromosomeschromosomes
Nuclear envelope Nuclear envelope disappearsdisappears
Spindle fiber Spindle fiber forms from the forms from the centriolescentrioles
Metaphase of MitosisMetaphase of Mitosis Chromosomes Chromosomes
begin to line up begin to line up at the equator of at the equator of the cellthe cell
Spindle fibers Spindle fibers attach to the attach to the centromerecentromere of of each sister each sister chromatid of the chromatid of the chromosomechromosome
Anaphase of Mitosis Anaphase of Mitosis Spindle fibers Spindle fibers
begin to pull begin to pull apart sister apart sister chromatids. chromatids. Each is now a Each is now a chromosomechromosome
Spindle breaks Spindle breaks down after thisdown after this
Telophase of MitosisTelophase of Mitosis
Each side now Each side now has a full set has a full set of of chromosomeschromosomes
Nuclear Nuclear envelope will envelope will reformreform
CytokinesisCytokinesis ““Cytokinesis”—Cytokinesis”—division division
of cytoplasm at the end of cytoplasm at the end of the cell cycle which of the cell cycle which cleaves the cell in halfcleaves the cell in half– Animal cells form a Animal cells form a
“furrow”“furrow”– Plant cells form a new Plant cells form a new
cell wallcell wall– Formation of two, Formation of two,
identical daughter cells identical daughter cells
Overall Cell Cycle ProcessOverall Cell Cycle Process IInterphase (G1, S, G2) and Mitosis nterphase (G1, S, G2) and Mitosis
((PProphase, rophase, MMetaphase, etaphase, AAnaphase, naphase, TTelophase) elophase) IPMATIPMAT
Cell Cycle AnimationCell Cycle Animation
Regulation of Cell CycleRegulation of Cell Cycle CyclinsCyclins- Proteins that - Proteins that
control cell divisioncontrol cell division Cancer cells don’t Cancer cells don’t
respond to the cyclin respond to the cyclin signals---uncontrolled signals---uncontrolled growth (tumors)growth (tumors) Benign tumors stay intactBenign tumors stay intact Malignant tumors spread Malignant tumors spread
throughout body throughout body (metastasize)(metastasize)
DNA (deoxyribonucleic acid)- a nucleic acid which stores genetic traits in the proteins it codes for
All living things contain DNA DNA is the blueprint for chemical
changes which take place in cells– Type of cell which is formed, (muscle,
blood, nerve etc) is controlled by DNA– Type of organism which is produced
(buttercup, giraffe, herring, human, etc) is controlled by DNA
How Much DNA Is In OUR Cells? Chromosome-strands of DNA coiled tightly
Human cell has 46 (23 pairs) 23 from Mom 23 from Dad
Other organisms have different numbers of chromosomes
2 Types of Cells Somatic cells –all body cells
except sex cells Diploidchromosomes are in
pairs 46=23 pairs for humans 1 set (23) from mom, 1 set (23)
from dad Gametes - sex cells
Egg & sperm Haploid no pairs (only 23
single chromosomes total)
body cells 46 chromosomes
sperm 23 chromosomes
egg 23 chromosomes
If all body cells contain the same # of chromosomes, why are all cells so different?
Different cells make different proteins due to different “active” segments of DNA– Heart cells make proteins needed for the heart to work
properly– Brain cells make proteins needed for the brain to work
properly
Human Chromosomes
Nucleotides- subunits of DNA made of:
– 1. Phosphate (PO4)– 2. A ring shaped sugar (deoxyribose)– 3. Nitrogen base
Nucleotides
The phosphate group is the same in each nucleotide
It contains the elements phosphate and oxygen
Phosphate Group
The ring-shaped sugar is the same in all nucleotides of DNA
– This sugar in DNA nucleotides is deoxyribose
– It is composed mainly of carbon and hydrogen
Later you will see there is another nucleic acid called RNA in which the sugar is ribose
Ring Shaped Sugar
They are “nitrogenous” because they contain nitrogen
The 4 bases that a DNA nucleotide can have are– Adenine (A)
– Thymine (T)
– Cytosine (C)
– Guanine (G)
Nitrogenous Bases
These 3 subunits combine to form 4 possible nucleotides in DNA
For example:
Entire Nucleotides
adenine
deoxyribose
PO4
PO4
PO4
PO4
PO4
sugar-phosphate backbone
bases
When many of these nucleotides monomers are joined together, which creates a nucleic acid molecule called DNA
Sequence and length of the nucleotide chains determine the proteins the DNA codes for
Two types of nucleic acids are found in living organisms
– DNA– RNA
A Nucleic Acid Strand
DNA usually consists of two strands of nucleotides bonded together, like a ladder– The sugar-phosphate chains are the
outside “rails”– The strands are held together by
chemical bond “rungs” between the bases
In humans there are approximately 3 billion nucleotides in each strand
DNA Structure
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
Strand #1 Strand #2
Chargaff’s Rule He measured amounts of each base in various organisms
and found:– % of adenine (A) = % thymine (T)
– % of cytosine (C) = % guanine (G)
Chargaff’s rule told us that A bonds to T and C bonds to G If 20% of strands is A, what %T? %C?
Adenine Thymine
Cytosine Guanine
PO4
PO4
PO4
thymine
PO4
PO4
PO4
PO4
adenine
cytosine
PO4
guanine
Strand #1 Strand #2
Hydrogen bonds between bases hold two strands together
3D Structure of DNA Discovered by Watson and Crick
– Double helix- 2 strands of nucleotides bonded together and twisted
– Discovery of this 3D structure helped us determine the exact function of DNA
sugar-phosphatechain
bases
What is DNA Replication? Replicate = make “exact” copies
– DNA replication- copying one double stranded DNA molecule into two genetically identical copies
– All DNA must be replicated before a cell can divide. Why?
– Replication Animation
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
The strands separate
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
Each strand builds up its partner by adding the appropriate nucleotides
Enzymes and Replication
Helicase- enzyme that unwinds DNA
DNA polymerase-enzyme that moves along each strand and brings in bases for new strand copy
DNA Replication Efficiency Replication is very fast and accurate, but there can
be a mistake made– Mutations-change in DNA– Mutagens- substances that cause mutations
• X-rays • Toxins• Drugs• UV light, etc.
Mutations 3 types of mutations that can
occur during DNA replication: – Insertions -extra
nucleotides– Deletions –missing
nucleotides– Substitutions –placement
of wrong nucleotides Can be helpful or harmful
mutations.
Insertion
Deletion
Substitution
How does DNA code for proteins?
A Gene Codes for One ProteinGene- a segment of DNA that codes for a protein
DNA has 1000’s of genes to make many different types of proteinsWhy are proteins important?
Protein - polymer of amino acids
aa—aa—aa—aa—aa—aa—aa—aa = protein
RNA (Ribonucleic acid) is Involved Stores the genetic code in
the nucleus Double stranded Sugar of DNA nucleotides
is deoxyribose A, C, G, T “DNA is DNA” Found in nucleus only
Transmits copies of the genetic code to the rest of the cellSingle strandedSugar of RNA nucleotides is riboseA, C, G, U (uracil) NO T!Different forms: mRNA, rRNA, tRNAFound all over cell
_____DNA____ vs._____RNA___
DNA vs. RNA
Part 1 of Protein Synthesis: Transcription
Transcription- copying of DNA triplets to mRNA codons in the nucleus– DNA complementary to mRNA– ATA-CGG-AAT (DNA triplets)
transcription in nucleus
UAU-GCC-UUA (mRNA codons)
Transcription
Translation
cytoplasm
Part 2 of Protein Synthesis: Translation:
Translation- converting mRNA copy to protein which occurs at ribosomes in the cytoplasm
UAU-GCC-UUA (3 mRNA codons) translation by ribosomes a.a.---a.a---a.a. (amino acids of protein)
cytoplasm
Whole Process ATA-CGG-AAT (DNA triplets) transcription in nucleus
UAU-GCC-UUA (3 mRNA codons) translation at ribosomesa.a.-a.a-a.a. (amino acids of protein)
tyrosine-alanine-leucine ??????
How do we know what amino acid results? The Codon Chart!!!Protein Synthesis and Pain—What is a
Protein?
The Codon Chart***How do we use the chart? There are 2 clues.
Amino Acids Where do our cells get
these amino acids to build the proteins?– From FOOD!– We eat proteins, then these
proteins are broken down (metabolized) into amino acids in our stomach.
– We reuse these amino acids to build other proteins.