1 Lecture 2 Cell, Genes and phenotype

2 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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4 Plasma Membrane Model

5 Nucleus and Nuclear Membrane

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

7 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.

8 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.

9 Endomembrane System

10 Mitochondria- The “powerhouse” Mitochondria are double-membrane organelles involved in cellular respiration. – Site of ATP production.

11 Cellular Respiration

12 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.

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

14 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.

15 Cellular Metabolism Cellular metabolism includes all the chemical reactions that occur in a cell. – Often organized into metabolic pathways.  Most regulated by feedback inhibition.

16 Enzymatic Action

17 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.

18 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.

19 DNA Location and Structure

20 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

21 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.

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

23 Can DNA replication cause mutations?

24 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.

25 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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27 How is the Sex of a Child Determined? Fetus development Genes and environment Sexual characteristics

28 Do chromosomes help determine sex? Sex chromosomes Human sex ratio – Sex ration at birth 1:1.05 – Young males die early – Females live longer

29 Chromosomes Male Karyotype

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32 Gametogenesis

33 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.

34 Genetic Inheritance

35 Dominant/Recessive Traits Forming the Genes. – Reduction of chromosome number occurs when pairs of chromosomes separate as meiosis occurs.

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