DNA and Chromosomes - PowerPoint PPT Presentation

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DNA and Chromosomes

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DNA and Chromosomes DNA is present in such large amounts in many tissues that it s easy to extract and analyze. But where is DNA found in the cell? – PowerPoint PPT presentation

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Title: DNA and Chromosomes


1
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?

2
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.

3
Prokaryote (Bacteria)
4
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

5
Eukaryote
6
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.

7
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.

8
Eukaryotic Chromosome
9
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.

10
How to read the code.
11
How does DNA make proteins?
  • DNA
  • (replication)
  • RNA
  • (transcription)
  • Proteins
  • (translation)

3 STEPS
12
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.

13
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??

14
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.

15
RNA vs. DNA
  • DNA replication
  • ATCGGTACTATCTATGTA
  • TAGCCATGATAGATACAT
  • RNA transcription
  • AUCGGUACUACUAUGUA
  • Biggest difference RNA has uracil instead of
    thymine (U instead of T)

16
RNA vs. DNA
17
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.

18
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.

19
STEP 3 Translation
  • Break RNA into codons LIKE
  • AUC/AGC/UAC/UGU/AUG
  • Use codon chart to TRANSLATE amino acid sequece

20
Translation
  • During translation, the cell uses information
    from messenger RNA to produce proteins.

21
3 Types of RNA
  • There are three main types of RNA messenger RNA,
    ribosomal RNA, and transfer RNA.

22
Replication
Translation
Transcription
23
KARYOTYPE
24
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25
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.

26
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?

27
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.

28
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29
Development and Differentiation
  • P)312

30
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