Cell Cell ReproductionReproduction

Binary Fission and Binary Fission and

The Cell CycleThe Cell Cycle

Prokaryotes vs Prokaryotes vs EukaryotesEukaryotes

1.1. Prokaryotes = Binary FissionProkaryotes = Binary Fission Have no nucleusHave no nucleus DNA in a simple loopDNA in a simple loop

2.2. Eukaryotes = The Cell CycleEukaryotes = The Cell Cycle Cells with a nucleusCells with a nucleus Linear DNA (has beginning and end)Linear DNA (has beginning and end)

Billions of Bacteria come Billions of Bacteria come from billions of bacteriafrom billions of bacteria

Binary Fission: Binary Fission: Simple Prokaryotic cell Simple Prokaryotic cell

(bacterial) division (bacterial) division

Definition:Definition: Process of cell Process of cell

division that division that produces identical produces identical offspring in offspring in prokaryotic cells. prokaryotic cells. (ex. bacteria)(ex. bacteria)

Binary Fission-2 Steps:Binary Fission-2 Steps:

1.1. Circular DNA unzips and copies itselfCircular DNA unzips and copies itself

2.2. Cell splitsCell splits

Binary FissionBinary Fission

The Cell CycleThe Cell Cycle

How do you grow?????How do you grow?????

Living things are often made of TRILLIONS of Living things are often made of TRILLIONS of cells cells

These cells are often:These cells are often: dyingdying

being worn away or being worn away or

the organism may be growing and needs more the organism may be growing and needs more cells… cells…

So, where do all these cells come from?So, where do all these cells come from?

The Cell Cycle that’s The Cell Cycle that’s where…where…

Cell Cycle (Eukaryotes)Cell Cycle (Eukaryotes)

Definition: Definition: The repeated sequence of growth and The repeated sequence of growth and

division required to strategically division required to strategically maneuver the nucleus, chromosomes maneuver the nucleus, chromosomes and organelles before the cell can and organelles before the cell can properly divide. properly divide.

Different Forms of DNA in Different Forms of DNA in the Cell Cyclethe Cell Cycle

1.1. ChromosomesChromosomes

2.2. ChromatinChromatin

3.3. ChromatidsChromatids

ChromosomesChromosomes

Definition:Definition: SUPERCOILEDSUPERCOILED DNA DNA

Structure:Structure: a a singlesingle coiled DNA molecule coiled DNA molecule

OR OR after replicationafter replication, it may be , it may be twotwo coiled DNA coiled DNA molecules held together at the center. molecules held together at the center.

The area it is held together is called The area it is held together is called ““centromerecentromere””

ChromosomesChromosomes

Chromatin:Chromatin: Nuclear DNA in a Nuclear DNA in a looseloose, “spaghetti-like” , “spaghetti-like”

structure structure during during InterphaseInterphase of the cell cycle. of the cell cycle.

DNA DNA before before it is super-coiled into it is super-coiled into chromosomeschromosomes

Chromatin:Chromatin:

Chromatid: Chromatid:

Each DNA molecule in the chromosome Each DNA molecule in the chromosome …therefore, each replicated chromosome …therefore, each replicated chromosome has 2 chromatids.has 2 chromatids.

NOTE: Chromosomes, Chromatin and NOTE: Chromosomes, Chromatin and Chromatids are all made of the same DNA, it’s Chromatids are all made of the same DNA, it’s just different shapes at different times of the just different shapes at different times of the cell cycle.cell cycle.

ChromosomesChromosomes

Phases of the Cell CyclePhases of the Cell Cycle

G1 (Gap 1 or Growth 1):G1 (Gap 1 or Growth 1): Cell growthCell growth

All routine functions of the cellAll routine functions of the cell S (Synthesis):S (Synthesis):

DNA CopiedDNA Copied Individual chromosomes consist of 2 chromatids attached at the Individual chromosomes consist of 2 chromatids attached at the

centromerecentromere G2 (Gap 2 or Growth 2):G2 (Gap 2 or Growth 2):

Growth and Preparation for MitosisGrowth and Preparation for Mitosis Organelles replicate, microtubules are reassembledOrganelles replicate, microtubules are reassembled

MM Mitosis:Mitosis: Nucleus divides into 2 nucleiNucleus divides into 2 nuclei

CC Cytokinesis:Cytokinesis: Cytoplasm divides into 2 cellsCytoplasm divides into 2 cells

Phases of the Cell CyclePhases of the Cell Cycle

Phases of the Cell CyclePhases of the Cell Cycle

How many chromosomes How many chromosomes does a cell have? does a cell have?

HomologuesHomologues:: two chromosomes that code for the same two chromosomes that code for the same

genetic traits (ex. eye color, etc)genetic traits (ex. eye color, etc) Two options in a cell:Two options in a cell:

1. Two homologues (diploid)1. Two homologues (diploid) 2. One homologue (haploid)2. One homologue (haploid)

Haploid vs DiploidHaploid vs Diploid

Humans have 23 pairs of homologues in all cells Humans have 23 pairs of homologues in all cells except sex cells except sex cells This is called This is called diploiddiploid or or 2N 2N

N stands for the number of unique chromosomesN stands for the number of unique chromosomes These non–sex cells are called “These non–sex cells are called “somatic somatic cellscells””

That means human somatic cells have 46 totalThat means human somatic cells have 46 total

Sex Cells: Sex Cells: Haploid Haploid or N or N (think “half”). (think “half”). This is how many are in sex cellsThis is how many are in sex cells Sex Cells are called “Sex Cells are called “gametesgametes.” (ex. egg and sperm).” (ex. egg and sperm)

Human Sex Cells have 23 chromosomes in them.Human Sex Cells have 23 chromosomes in them.

Is Ms. Barrett the best science teacher here Is Ms. Barrett the best science teacher here at Skyline? at Skyline?

How about Mr. Hodge? How about Mr. Hodge? Nelson? Nelson?