Chp 6 - Biology

Genome

• A cell’s complete set of DNA

• Found in the Nucleoid

Plasmids

there are EXTRA DNA molecules

• LARGER

• LINEAR (Long, Non-looped)

• Nucleus

• Chromatin

• Chromosome

In the Eukaryotic Cells (Genome)

• The Genome is ____

• LINEAR (Long, Non-looped)

• Found in the _____

• ____-> Relaxed form 

• ____-> Condensed Form

Chromosome

consists of a Long Strand of DNA containing many genes

Human Chromosome

this chromosome can have up to 500 million base pairs (Adenine-Thymine, Guanine-Cytosine) of DNA w/ Thousands of Genes

Nucleotide Monomer

Nucleic Acids

PO4 (phosphate group), Sugar, & a Nitrogenous Base

Thymine (T)

Complementary Nitrogenous Base Pairing in DNA

Adenine (A) pairs with?

Cytosine (C)

Complementary Nitrogenous Base Pairing in DNA

Guanine (G) pairs with?

DNA Structure

• Double Helix (like a twisted ladder)

• uses Hydrogen Bonding (Weak bond but many of them it’s a strong bond)

Genes

Sequences of DNA on a chromosome that CODE FOR A SPECIFIC PROTEINS, or RNA molecules (messenger RNA)

Genes

• ___are the Functional Units of Heredity

• ___is a REGION of DNA that codes for Proteins

• ___consist of a Distinct Sequence of Nucleotides (= DNA monomers) forming part of a Chromosome, arranged in a certain order to code for Protein Molecules which a Cell SYNTHESIZES

• ____code for Eye color, Hair color, Skin color, Sex, Body type, etc

Genes

• ___is a short piece of DNA

• ___tell the body how to build specific proteins

• about 20,000 ___ in each cell of the human body

• Together, they make up the blueprint for the human body & how it works

Genotype

A person’s genetic makeup is called a ____

Genome

this is the Entire Genetic Complement of an Organism (= all of the DNA)

46 chromosomes

Each Eukaryotic Species has a unique number of Chromosomes

how many chromosomes humans have?

an organism is more COMPLEX (smartness)

NUMBERS of Chromosomes DOES NOT mean

• Somatic 

• Gametes

Two Different Cell Types in a HUMAN

Somatic

(body cells) = Diploid = Full Complement of Chromosomes

Gametes

(sex cells) = Haploid = 1/2 the Number of Chromosomes

1. Somatic

2. 23 sets of Chromosomes

3. 2 Chromosomes

4. total of 46 Chromosomes

1. ___Cells are Diploid -> Two Chromosomes / set = 2n

2. Humans have ____

3. Each set has ____

4. Humans have a ____ in a Somatic (body) cell

1. Gamete

2. Two Haploid (n) ; Diploid (2n) State

1. ___Cells are Haploid -> One Chromosome / Set = n

2. When ____ cells meet (fertilization), the Organism is back to ____

23 Pairs of Homologous Chromosomes

There are ____ in a female Human Somatic Cell (2 X Chromosomes)

Karyotype

• These Chromosomes are viewed w/in the Nucleus (top), Removed from a cell in Mitosis (right), & Arranged according to Length (left) in an arrangement called a ____

• An individual’s complete set of chromosomes → organizes those chromosomes by Size, Shape, & Numbers

Homologous chromosomes

• ____are MATCHED PAIRS of Chromosomes in a Diploid (2n) Organism

• ____have the same genes but often have VARIATION among those genes

• One Gene is from Mom, One gene is from Dad (in each set) so it’s unlikely that you get the same genes from both unless Mom & Dad are very CLOSELY RELATED

• The SAME LENGTH

• Have the SAME GENES in the SAME LOCATION

• the centromere is in the same location, and genes are in the same locus but have variation

Each Chromosomes in a Pair are:

Locus (Loci plural)

The Location of a Gene is called a ___

Duplicated Homologous Chromosomes

Homologous Chromosomes

• You get One Chromosome from Mom & One from Dad in EACH SET

• In the Cell Cycle, the Chromosomes DUPLICATE

Sister Chromatid

An Identical Copy of a Chromosome that is attached is called a ___

Homologous Chromosomes

members of a Pair of Chromosomes that are ALIKE w/ Small Variations in Genes they Hold

(sister) Chromatids

Duplicated Chromosomes attached by a Centromere

Cell Cycle

• an Ordered Series of Steps that concludes w/ Two New Identical Daughter Cells

• DNA is copied & Divided evenly

To allow an Organism to GROW & REPAIR itself

Cell Cycle Purpose

Two Identical Daughter Cells

Cell Cycle Outcome

Interphase & Mitotic Phase

Cell Cycle TWO MAJOR PHASES

1. Interphase & Mitotic Phase

2. Interphase: G1, S, G2

3. Mitotic Phase: Mitosis + Cytokinesis

4. Mitosis 5 Stages: Prophase, Metaphase, Anaphase, Telophase (PMAT)

Cell Cycle

• To make Identical Cells to Replace Old Cells

  • Get DNA into the Cells to make it Organized

Mitosis PURPOSE

CONTINUING ; WRONG

Checkpoints of the Cell Cycle

• Checkpoints Prevent Cells from ____ the Cell Cycle when Something is _____

  • Ex: P53 will STOP the Cell Cycle at G1 if DNA is damaged

G1 Checkpoint (primary checkpoint)

• Assess DNA damage & nutrient availability

• the check point in which a cell checks if DNA was damaged during mitosis and if there is enough nutrients available to move forward with the cell cycle. The molecule p53 is used here to correct DNA damage or cause apoptosis.

G2 Checkpoint

• Check for Completion of DNA replication

• occurs to check if chromosomes lined up correctly during mitosis before being split to opposite side of the cell

M Checkpoint

• Assess Chromosome alignment & spindle connection

• occurs to check that DNA was replicated correctly in the previous phase

• G1 phase

• S phase

• G2 phase

Interphase (functions) consists of phases:

Interphase

• It takes up 90% of the Cell Cycle

• Most of the Cell Cycle is spent in ____

• Cell performs its usual functions

• Time spent in ____ varies by Cell type

First Gap Phase (G1 Phase)

The Cell Cycle - Interphase - G1

• Cell is in RECOVERY from Previous Division

• Cell DOUBLES its Organelles

• Cell GROWS in Size

• Cell ACCUMULATES Raw Materials for DNA synthesis

• Cell recovering from division, growing in size, doubling organelles

S Phase in The Cell Cycle

• S stands for SYNTHESIS 

  • Proteins associated with DNA are also DUPLICATED

  • Chromosomes enter _____ with 1 Chromatid EACH

  • Chromosomes leave _____ with 2 Identical Chromatids (Sister Chromatids) EACH

  • Sister Chromatids remain attached until they are SEPARATED during Mitosis

  • DNA is replicated

Interphase - S Phase

Which phase

• Each DNA molecule is attached by a CENTROMERE

• Sister Chromatids attached by Centromere

• DONT SEPARATE UNTIL MITOSIS

G2 Phase in The Cell Cycle

• ____is located b/t DNA Replication & Mitosis

• Cell Synthesizes Proteins, including Microtubules, necessary for Division

• The Cell “Double Checks” the Duplicated Chromosomes for error, making any NEEDED REPAIRS

• Cell continues to grow, forms microtubules in preparation for division

Interphase - G2

Second Gap Phase -> G2

• Replenishes Energy Spent in S Phase

• Synthesize Protein (microtubules) used to break apart the Sister Chromosomes

G0 (G Naught)

• This is the RESTING PHASE

• Some Cells ENTER & NEVER Duplicate

  • Cardiac Muscle Cells

  • Nerve Cells

• Some Cells STAY HERE until SIGNALED to Replicate

• Mitosis 

• Cytokinesis

Mitotic Phase Includes:

Mitosis

5 Stages where Chromosomes are Divided

Cytokinesis

• The Physical Separation of Cytoplasm into Two New Daughter Cells

  • Results in 2 Genetically Identical Daughter Cells

Prophase - Metaphase - Anaphase - Telophase

Phases of Mitosis (PMAT)

• 1) Mitosis 

  • Nuclear Division

  • Daughter Chromosomes distributed by the Mitotic Spindle to Two Daughter Nuclei

• 2) Cytokinesis

  • Division of the Cytoplasm

• Results in Two Genetically Identical Daughter Cells

M (Mitotic) Stage (PMAT + C)

S Phase

Chromosomes are being Synthesized & Replicated

G2

Check to make sure the Chromosomes are replicated properly & if they arent they are repaired -> if not the cell dies

Prophase

Phases of Mitosis

• Chromatin condenses into Chromosomes

• Nucleolus DISAPPEAR

• Centrosomes (2 Microtubule Rings called Centrioles / Mitotic Spindle Fiber Creators) move to Opposite Sides of the Cell

• Spindle Fibers form Microtubules

• Chromatin condenses, nucleus and nucleolus breakdown, mitotic spindle fibers form

Metaphase

Phases of Mitosis

• Chromosomes ALIGN on the Metaphase Plate in the Center of the Cell

• Chromosomes line up down the center

Anaphase

Phases of Mitosis

• Sister Chromatids are Pulled Apart by the Spindle Fibers

• Now called Daughter Chromosomes

• Sister chromatids separate forming daughter chromosomes.

Telophase

Phases of Mitosis

• OPPOSITE of Prophase

• Daughter Chromosomes reach the Opposite Side of Cell

• Chromosomes RELAX (Decondense)

• Nucleus & Nucleolus REFORM

• Spindle Fibers BREAK DOWN

• Chromosomes relax, nucleus and nucleolus reform, mitotic spindle fibers breakdown

Cytokinesis

• Second Phase of the Mitotic Phase

• Physical Separation of the Cell into Two Identical Daughter Cells

• Often begins in Anaphase

• This Process is DIFFERENT for Animal Cells Compared to Plant Cells

• Animals – actin creates a cleavage furrow. Plants – cell plate forms. Both – cells split

• CONTRACTILE RING of Actin Filaments forms at Metaphase Plate

• Contracts & Creates Cleavage Furrow

• This is where the Cells SPLIT

Cytokinesis In Animal Cells

• Rigid Cells Wall DONT Allow the Plant Cell to have a Contractile Ring

• Form a Cell Plate made of Vesicles & Cellulose (Cell Wall Material)

Cytokinesis In Plant Cells

Kinetochore, Kinetochore Microtubules, Centromere, Chromatids

Kinetochore

A Disc-Shaped Protein Structure associated w/ Duplicated Chromatids in Eukaryotic Cells where the Spindle Fibers attach during Cell Division to PULL Sister Chromatids APART

1. Metaphase

2. Prophase

3. Beginning of Cytokinesis

4. Interphase

5. Plant cell already divided

6. Plant cell already divided 

7. Anaphase

8. Interphase

9. Same as 3 

10. Metaphase

Pick out the Phase

• 1 -> Cytokinesis (late Telophase)

• 2 -> Anaphase

• 3 -> Interphase

• 4 -> Interphase after Cytokinesis (cell walls form in b/t)

• 5 -> Metaphase

Pick out the Phase

Cancer

• A Collective Name for Different Diseases

  • Caused by Uncontrolled Cell Division

Cell Cycle Checkpoints

• are VITAL to Maintain Cell Health

  • If Broken -> Leads to Cancer

Mutations

___occurring during S Phase lead to Cancer

Protein Malfunctioning

All Cancers ________ due to Mutations

Tumors

____result when Cells Divided UNCONTROLLABLY

Proto-Oncogenes

• GOOD Genes that Code for POSITIVE Cell Cycle Regulators (proteins)

  • They PUSH the Cell Cycle FORWARD (keep dividing)

  • BUT, when they Mutate ______ become Oncogenes (causes cancer)

  • We need these!

Oncogenes

• BAD Genes that Cause a Cell to Develop Cancer

  • If a Proto-Oncogene is Mutated, it may become an _____

Tumor Suppressor Genes

• Genes that control the NEGATIVE Cell Cycle Regulator Proteins

  • They STOP the Cell Cycle when it SHOULDNT GO ON (stop dividing)

• We need these too!

• Ex: p53

All Cancers

Mutated P53 Genes lead to HALF of _____ Identified so far

1. MONITOR DNA

2. Repair Mechanisms

3. Apoptosis

1. The Role of P53 is to ____

2. If Damage is Detected, P53 TRIGGERS ______

3. If Repairs are UNSUCCESSFUL, P53 signals _____

• DNA ; Apoptosis

• Cancerous

• A Cell w/ an Abnormal P53 Protein CANNOT Repair ___ & CANNOT signal _____

• Cells w/ Abnormal P53 can become _____

• MONITORED

• MUTATED

• arrest cell growth ; repair

• Apoptosis

• p53 gene codes for the p53 protein that _____ the cell cycle

• Over 50% of cancers are caused by _____ p53 proteins

• P53 will _____ & begin to ____ damaged DNA

• If can’t fix the damage in the cell, it will lead to ____ (programmed cell death)

• = Tumor suppressor protein

Tumor Suppressing Protein p53

• The p53 Gene provides Instructions for making a Protein called ____

• Protein ACTS as a Tumor Suppressor → Regulates Cell Division by Keeping Cells FROM Growing & Dividing (proliferating) TOO FAST or in an UNCONTROLLED Way

Apoptosis

• Programmed Cell Death

  • It involves a Sequence of Cellular Events that bring about the Destruction of the Cell

• INCREASES

• DECREASES

Mitosis & Apoptosis are Opposing Forces

• Mitosis ____ Cell Number

• Apoptosis ____ Cell Number

Binary Fission

• Asexual (w/out sex) Reproduction in which Cells Divide into 2 Identical Daughter Cells w/out going through Eukaryotic Cell Division (Interphase & Mitotic Phase)

• QUICKER & LESS Complicated than Sexual Reproduction (don’t need a partner)

• Prokaryote Asexual Reproduction

  • Results in Genetically Identical Cells

• THIS IS NOT MITOSIS

• Circular Chromosome BINDS to the Plasma Membrane at a Special Site

• DNA begins Replication at the Origin in BOTH DIRECTIONS

• Each origin moves TOWARD OPPOSITE ENDS of the Cell

• Cell ELONGATES

• A Septum (Cleavage Furrow) forms & Cell Walls Form

Binary Fission Steps