Cell Reproduction

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.