1 Lecture 2 Cell, Genes and phenotype. 2 Cell, Gene expression and phenotype Cellular Organization DNA and RNA Structure and Function Gene expression

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Lecture 2

Cell, Genes and phenotype

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Cell, Gene expression and phenotype• Cellular Organization• DNA and RNA Structure and Function• Gene expression• How is sex determined• Chromosomes• Genotype & Phenotype• Dominant & Recessive traits

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Plasma Membrane Model

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Nucleus and Nuclear Membrane

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Ribosomes

• Ribosomes are found singly or in groups (polyribosomes) in the cytoplasm.– Function in protein synthesis.

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The Endomembrane System- also function in protein synthesis

• Endoplasmic Reticulum.– System of membranous channels and

saccules.Rough ER is studded with ribosomes

and synthesizes proteins.Smooth ER synthesizes phospholipids,

as well as various other functions.

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The Endomembrane System- process final products and monitor incoming vesicles

• The Golgi Apparatus.– Consists of a stack of three to twenty

curved saccules, along with vesicles.Receives protein and or lipid vesicles

that bud from the ER.• Lysosomes.

– Membranous sacs produced by the Golgi apparatus that contain hydrolytic digestive enzymes.

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Endomembrane System

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Mitochondria- The “powerhouse”

• Mitochondria are double-membrane organelles involved in cellular respiration.– Site of ATP production.

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Cellular Respiration

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The Cytoskeleton

• The cytoskeleton is formed of several types of filamentous structures that give the cell its shape and organelles the ability to move about the cell.– Microtubules.– Actin Filaments.

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Centrioles

• Centrioles are short cylinders composed of microtubules that are involved in spindle formation during cell division

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Cilia and Flagella

• Cilia and flagella (cilium, flagellum) are projections that move in an undulating or whipping fashion.– Cilia tend to be shorter while flagella tend

to be longer.

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Cellular Metabolism

• Cellular metabolism includes all the chemical reactions that occur in a cell.– Often organized into metabolic pathways.

Most regulated by feedback inhibition.

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Enzymatic Action

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The Nucleus

• The nucleus stores genetic information that determines body cell characteristics and metabolic functioning.

• Nucleus is separated from the cytoplasm by a nuclear envelope.

Contains nuclear pores to permit passage of proteins and ribosomal subunits.

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DNA and RNA Structure and Function

• DNA is the genetic material found principally in chromosomes.– In between cell divisions, chromosomes

exist in long fine threads of chromatin.When a cell is about to divide,

chromosomes coil and condense.

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DNA Location and Structure

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DNA Structure and Replication

• DNA is a sequential series of joined nucleotides.– Sugar (deoxyribose), phosphate, and base.

Adenine (A).Thymine (T).Cytosine (C).Guanine (G).

nucleotides

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DNA Structure and Replication

• DNA is a double helix with a sugar-phosphate backbone and bases projecting between the backbones.– Exhibits complementary base pairing.

A-T.G-C.

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DNA Replication/ cell division Mitosis and Meiosis (replacing cells or making babies)

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Can DNA replication cause mutations?

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Structure and Function of RNA- protein synthesis (the way we look)

• RNA is made up of nucleotides containing the sugar ribose and the base uracil in place of thymine.– Single stranded.

RNA is a helper to DNA allowing protein synthesis.

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Gene Expression

• Structure and Function of Proteins.

– Proteins are composed of amino acids.

Proteins differ because the number and order of their amino acids differ.

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How is the Sex of a Child Determined?

• Fetus development• Genes and

environment• Sexual characteristics

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Do chromosomes help determine sex?

• Sex chromosomes• Human sex ratio

– Sex ration at birth 1:1.05

– Young males die early

– Females live longer

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Chromosomes





Male Karyotype

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Gametogenesis

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Genotype and Phenotype

• Genotype refers to an individual’s genes.– Alleles are alternate forms of a gene.

Dominant alleles are assigned uppercase letters, while recessive alleles are assigned lowercase letters.

Homozygous Dominant = EE. Homozygous Recessive = ee. Heterozygous = Ee.

• Phenotype refers to an individual’s physical appearance.

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Genetic Inheritance

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Dominant/Recessive Traits

• Forming the Genes.– Reduction of chromosome number occurs

when pairs of chromosomes separate as meiosis occurs.

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1 Lecture 2 Cell, Genes and phenotype. 2 Cell, Gene expression and phenotype Cellular Organization DNA and RNA Structure and Function Gene expression