DNA and Chromosomes

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DNA and Chromosomes

• DNA is present in such large amounts in many
  tissues that its easy to extract and analyze.
  But where is DNA found in the cell? How is it
  organized?

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Prokaryotes

• What are the two types of cells?
• Prokaryotic cells lack nuclei and many of the
  organelles found in eukaryotes.
• Most prokaryotes have a single circular DNA
  molecule that contains all of the cells genetic
  info.
• This large molecule is usually referred to as the
  cells chromosome.

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Prokaryote (Bacteria)
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Eukaryotic DNA

• Eukaryotic DNA is a bit more complicated. Many
  eukaryotes have as much as 1000 times the amount
  of DNA as prokaryotes.
• Eukaryotic DNA is usually found in the cells
  nucleus in the form of a of chromosomes.
• The of chromosomes varies widely.
• EX) humans 46 Drosophila (Fruit fly) - 8

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Eukaryote
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DNA Length

• DNA molecules are surprisingly long. The
  chromosome of the prokaryote E. coli, which can
  live in the human colon (large intestine),
  contains 4,639,221 base pairs.

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Chromosome Structure

• The DNA structure of a human cell is packed even
  more tightly. Matter of fact it is 1000 times
  longer than that of a bacterium cell.
• Eukaryotic chromosomes contain both DNA and
  protein tightly packed together to form a
  substance called chromatin.
• The protein (histone) allows for the DNA to
  tightly pack around so that it can fit.

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Eukaryotic Chromosome
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DNA Replication

• During DNA replication, the DNA molecule
  separates into two strands, then produces two new
  complementary strands following the rules of base
  pairing. Each strand of the double helix of DNA
  serves as a template, or model, for the new
  strand.

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How to read the code.
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How does DNA make proteins?

• DNA
• (replication)
• RNA
• (transcription)
• Proteins
• (translation)

3 STEPS
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RNA and Protein Synthesis

• The double helix structure explains how DNA can
  be copied, but it does not explain how a gene
  works.
• The first step part of the nucleotide sequence in
  decoding these genetic messages is to replicate
  from DNA to RNA, or ribonucleic acid.

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STEP 1 DNA Replication

• During DNA replication, the DNA molecule
  separates into two strands, then produces two new
  complementary strands following the rules of base
  pairing. Each strand of the double helix of DNA
  serves as a template, or model, for the new
  strand.
• REMEMBER??

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The Structure of RNA

• There are three main differences between RNA and
  DNA.
• 1. The sugar in RNA is ribose instead of
  deoxyribose
• 2. RNA is generally single-stranded
• 3. RNA contains uracil in place of thymine.

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RNA vs. DNA

• DNA replication
• ATCGGTACTATCTATGTA
• TAGCCATGATAGATACAT
• RNA transcription
• AUCGGUACUACUAUGUA
• Biggest difference RNA has uracil instead of
  thymine (U instead of T)

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RNA vs. DNA
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RNA

• You can think of an RNA molecule as a disposable
  copy of a segment of DNA
• In many cases, an RNA molecule is a working copy
  of a single gene.

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STEP 2 Transcription

• RNA is produced by a process known as
  Transcription. (Elves dont understand Santa)
• During transcription, RNA polymerase binds to DNA
  and separates the DNA strands. RNA polymerase
  then uses one strand of DNA as a template on
  which nucleotides are assembled into a strand of
  RNA.

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STEP 3 Translation

• Break RNA into codons LIKE
• AUC/AGC/UAC/UGU/AUG
• Use codon chart to TRANSLATE amino acid sequece

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Translation

• During translation, the cell uses information
  from messenger RNA to produce proteins.

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3 Types of RNA

• There are three main types of RNA messenger RNA,
  ribosomal RNA, and transfer RNA.

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Replication
Translation
Transcription
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KARYOTYPE
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BREAKING THE CODE

• Welcome to the FBIs new code breaking division.
  Your mission if you choose to accept it is to
  break the code given to you. We know that this
  code has something to do with the genetic make
  up of the notorious villain, Coach Bossenbroek
  (AKA coolest guy on the planet), the problem is
  we dont know how to find the amino acid
  sequence. This message will self distruct.

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Mutations

• Now and then cells make mistakes in copying their
  own DNA, inserting a new base or even skipping a
  new base as it is being put together.
• WHAT DO YOU THINK WOULD HAPPEN?

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Kinds of Mutations

• Point Mutation Gene mutations involving changes
  in one or a few nucleotides are known as point
  mutations.
• Frameshift Mutation If a nucleotide is added or
  deleted, the bases are shifted for every codon
  that follows.
• THESE ARE GENE MUTATIONS.

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Development and Differentiation

• P)312

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