Chapter 3: Biological basis of life: genetics, cells, DNA 1 Types - - PowerPoint PPT Presentation

Chapter 3: Biological basis of life: genetics, cells, DNA

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Types of eukaryotic cells

Somatic cells: cells of the body (hair, skin, tissue) Sex cells: (in mammals), ova and sperm (i.e., gametes)

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Organelles

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DNA

• Directs cell activities
• Building blocks of all life-forms

Nucleotide structure: Sugar + phosphate + base pairs Adenine - Thymine Guanine - Cytosine Bases form complementary bonds

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DNA replication

• 1. DNA unzips
• 2. Exposed bases attract

complementary nucleotides

• 3. Two "parent" strands = templates for

new strands

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DNA replication

• 1. DNA unzips
• 2. Exposed bases attract

complementary nucleotides

• 3. Two "parent" strands = templates for

new strands

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Proteins

Structural proteins (keratin, collagen) Functional… regulate chemical activities (enzymes, hormones)

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Proteins

• Made of amino acid chains

Amino acids

• Sequence and number determine protein function

Triplets: sequence of 3 DNA bases specifies amino acids

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DNA vs RNA

RNA

• Single-stranded
• Uracil base instead of thymine

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Protein synthesis

Part 1 (transcription) in the nucleus...

• mRNA copies DNA bases three at a time (triplets) into codons

Part 2 (translation) in the cytoplasm with ribosomes...

• tRNA binds amino acids with complementary codons

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Protein examples

Hormones

• Produced by specialized cells
• Influence chemical reactions
• Regulates various cell functions

Hemoglobin binds oxygen to red blood cells...

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