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DNA: The Molecule of Heredity

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Presentation on theme: "DNA: The Molecule of Heredity"— Presentation transcript:

1 DNA: The Molecule of Heredity

2 DNA Structure Deoxyribonucleic acid.
A macromolecule composed of two strands of monomers called nucleotides. These strands are joined in the middle by hydrogen bonds. The strands twist around one another forming a double helix. Twists to the right.

3 Nucleotide Structure 5-C sugar – deoxyribose Phosphate group
Nitrogen containing base -4 of two types Adenine Guanine Cytosine Thymine

4 Types of Nitrogen Bases
Pyrimidines – have one ring in their structure Thymine Cytosine Purines – have two rings in their structure Adenine Guanine

5 Nitrogen Base Pairing Bases pair in a specific pattern.
A purine always bonds to a pyrimidine Adenine bonds to thymine. Guanine bonds to cytosine.

6 Nitrogen Base Pairing The bases are held together by weak hydrogen bonds.  The sides of the DNA ladder are composed of alternating sugar and phosphate and are called “backbones”.

7 Functions of DNA DNA must be able to copy itself exactly. - This process is called REPLICATION - Enzymes control the process. DNA is the molecule of heredity. - It provides instructions for cell functioning and is a blueprint for the production of proteins that do the work of the cell.

8 Replication – Overview
·  DNA “unzips” down its H-bonds ·  One strand then acts as a template for the production of a new strand ·  Each new DNA molecule has one old strand of nucleotides and one new strand.

9 Control Of Cell Activities
DNA is copied into RNA. (Transcription) RNA in turn controls the production of proteins. (Translation) Proteins then do the work of the cell.

10 RNA Like DNA, Ribonucleic acid is also made up a sugar, phosphate group and nitrogen bases. But there are some major differences-- The sugar in RNA, is Ribose. RNA is single stranded the nitrogen bases consist of Uracil (U), Adenine (A), Guanine (G) and Cytosine (C). Uracil and Adenine = Base Pair Guanine and Cytosine = Base Pair

11 TAKS PRACTICE: Question 1

12 Question 2 4 DNA passes information to RNA during the process of —
F transcription G active transport H regeneration J osmosis F

13 Question 3 5 Which of the following must occur before DNA replication can take place? A Translation of DNA into amino acids B Separation of the DNA molecule into codons C Transformation of DNA into RNA D Separation of the DNA double helix D

14 Question 4 3 If a cat has 38 chromosomes in each of its body cells, how many chromosomes will be in each daughter cell after mitosis? F 11 G 19 H 38 J 76 H

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