Cell cycle, DNA, and replication

BIO…LIFE….

THINK ABOUT THIS:

What do we do in our lifetime?

What are the major stages of our life?

What are the Major stages of physical development in our lives? What would it look like

if we put this into a pie

chart?

Imagine you are a bacteria:What are the major stages in your life?

TRY ME: What is A? B? C? What is D/E/F/G collectively

called? What is D? What is E? What is F? What is G?

The life of a cell Cells have a life cycle just like we do- born, grow, reproduce,

and die. They only spend part of

their life cycle reproducing (M)- mitosis

Cell Cycle

1. Interphase (G1, S, G2) – cell grows, prepares to divide (G phases) and DNA replicates (S phase)

2. Mitosis: nucleus divides; each nuclei winds up with the same # and kind of chromosomes as the parent (P-M-A-T)

3. Cytokinesis: division of cytoplasm

COMING UP IN THIS CLASS… In the upcoming months, we will be analyzing what happens stages

in great detail. Which stage do you think the following upcoming material will focus on?

Topics to cover:- Cell cycle and events- DNA structure and replication?- DNA structure - Cell reproduction (asexual- bacteria)?- Cell reproduction (growth- multicellular)?- DNA and making proteins- Proteins and regulation of the cell cycle- What happens when things go wrong….

NUCLEIC ACIDS: The 4th category of Biomolecules

What were the 4 macromolecules/biomolecules? What are monomers? Polymers? What is the name of the process that builds monomers to

polymers called? What is the reverse process called?

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Nucleic Acids are the chemical link between generations dating back to the beginning of life on earth.

 

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A nucleic acid is a complex macromolecule that stores information in cells in the form of a code.

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Terminology: What is the difference and relationship between the following:

- DNA -nucleus- Chromosomes - chromatid- Genes - chromatin- Centromere -histones- nucleotides

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What are chromosomes???13Nucleotides make up DNA

DNA winds into ChromatinChromatin condenses into Chromosomes are composed of chromatids held together at the centromereChromosomes contain GenesGenes are sections of DNADNA is made of nucleotides

Chromosomes contain Instructions for making YOU!!!

Chromosome - DNA Chromosome- Chromatid

Where is it located in the cell? NUCLEUS! How is it arranged?

Figure 9-4 Chromosome structure

DNA double helix

histone proteins

DNA woundaround histoneproteins

Loops attachedto a protein scaffold;this stage of partialcondensation typicallyoccurs in a nondividingcell

Coiled DNA/histone beads

protein scaffold

Foldedchromosome,fully condensedin a dividing cell

NUCLEIC ACID

What is the monomer of nucleic acids called? What components does it have? What are the 2 major nucleic acids?

What do they do? What ways are they similar in structure? What 3 ways do they differ in structure?

THEME….how is the structure related to their function?

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MONOMER: Nucleic acids are made of long chains of nucleotides.

  Nucleotides are made of three components:

1. sugar

2. phosphate group

3. nitrogen base

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Examples of nucleic acids are :

1. DNA

2. RNA

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DNA = deoxyribonucleic acid

 

its components are:

1. deoxyribose (sugar)

2. phosphate group

3. nitrogen base

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Purpose? To code for everything in your body...genetic blueprint!

The Components and Structure of DNA

There are four kinds of bases in in DNA:

adenine guanine cytosine thymine

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Adenine (A) – Thymine (T)

Guanine (G) – Cytosine (C)

A and G are purines (AGgies eat Purina)

C and T are pyrimidines

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 The paired nitrogen bases formed two long strands of nucleotides that compliment each other.

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Nitrogen Bases are connected

between sugars and phosphatesThey declared, “This structure is

a “double helix”

The structure is antiparallel (upsidedown).

This causes a problem in replication

Because replication is a one way

direction.

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DNA Double Helix 25

WHO DISCOVERED THIS??? …..its complicated

IV. Watson and Crick (1953) /Wilkins and Franklin

A. Watson and Crick 1. double helix model of DNA based on the work of other scientistsB. Maurice Wilkins and Rosalind Franklin 1. x-ray diffraction photographs of DNA helped Watson and Crick develop their model 2. Watson, Crick and Wilkins received Nobel Prize in l962 (Franklin died in 1958 and could not be named for the award)

X-ray Diffraction Photo Rosalind Franklinof DNA) and Maurice Wilkens

DNA Double Helix Watson and Crick

V. Erwin Chargaff - 1949

CHARGAFF:

Percent of nitrogen bases that pair with each other (complementary bases) is the same

1. percent adenine equals percent thymine

percent guanine equals percent cytosine

2. implied base pairing rules

DNA forms chromosomes, units of genetic information which pass from parent to offspring.

DNA is wound into structures called chromosomes during cell division

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If you unraveled all your chromosomes from all of your cells and laid out the DNA end to end, the strands would stretch from the Earth to the Moon about 6,000 times.

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RNA has a different sugar than DNA RNA = ribonucleic acid

It’s components are :

1. ribose (sugar)

2. phosphate group

3. nitrogen base

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It also has different bases than DNA

adenine --- uracil

cytosine --- guanine

  RNA is also single stranded, not double stranded like DNA.

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DNA RNA

- Double stranded - Single stranded

- Sugar = deoxyribose

- Sugar = ribose

- Adenine pairs with Thymine

- Adenine pairs with Uracil

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I. Why Must DNA Replicate?  Every time a cell divides, it must first

make a copy of it’s chromosomes. Therefore, each cell can have a complete setof chromosomes.

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Without replication, species could not survive and individuals could not successfully grow and reproduce.

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II. How DNA Replicates

DNA is a molecule composed of TWO strands, each consisting of a sequence of nucleotides.

The order of the nitrogen bases on one strand mandates the sequence of bases on the complementary strand.

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If you know the bases on one strand, you can predict which bases will occur on the complementary strand.

A ----- G -----T -----C -----C -----C -----T -----

During Replication each strand serves as a template to create a new strand.

TCAGGGA

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III. Steps In Replication

1) Helicase break down the hydrogen bonds between the two DNA strands, unzipping the molecule

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DNA Replication

1. Helicase break the hydrogen bonds between the bases so the chains of DNA can separate or unwind

2) As the DNA unzips,

SSB (single strand binding protein holds the strands down.

3) Primase(RNA) makes start platforms

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4) DNA polymerase adds nucleotides (from surroundings in the nucleus) bond to the single strands by base pairing (A-T, G-C)

SEMI- CONSERVATIVE REPLICATION:** The result of this process is the formation of TWO

DNA molecules, each identical to the original molecule- with one old strand and one new strand.

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2. Other enzymes add new nucleotides, which form new hydrogen bonds with their complimentary nucleotide.

Red = original strandBlue = new strand

DNA Replication

DNA Replication

Results in 2 semi-conservative double stranded molecules

WHAT IS THE ROLE OF:

Helicase-

SSB-

Replication fork-

DNA Polymerase-

ANIMATIONS OF DNA REPLICATION

http://www.bioteach.ubc.ca/TeachingResources/MolecularBiology/DNAReplication.swf

http://www.mcb.harvard.edu/Losick/images/TromboneFINALd.swf

http://highered.mcgraw-hill.com/sites/0072556781/student_view0/chapter11/animation_quiz_2.html

http://www.sinauer.com/cooper/4e/animations0601.html

AMEOBA SISTERS:https://www.youtube.com/watch?v=5qSrmeiWsuc&index=1&list=PLwL0Myd7Dk1F1pp-DaLx3ygO_7xA-yyd4

1. What are the two types of nucleic acids?2. What are the three components of a nucleotide?

3. What are the similarities between DNA and RNA? What are the differences?

4. Describe the process of DNA replication.5. Why does a DNA molecule undergo replication?

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