Bio 30

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Genetics A Laboratory Manual

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Weekly Lab

A -3l

Tuesday, 10-1

Weekly Lecture

A

Wednesday, 7-8

Friday, 7-8

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Lab 1

Introduction

Genetics

Interphase

occupies most of the cells life cycle (90%) and subdivided into three sections G-1 phase, S phase, and G-2 phase

Gap 1

Cell growth, protein synthesis, normal cell
functions, about 11 hours

S phase (synthesis)

DNA replication, up to 7 hours

Gap 2

Cell growth, protein synthesis, 4 hours

M-phase

Cell Division

divided into two parts nuclear division (mitosis or meiosis) and
cytokinesis (10%)

Mitosis

Undergone by all somatic(body) and germ

Prophase

Nuclear membrane breaks down, spindle fibers begin to form, chromosomes condense

Metaphase

Spindle fibers formed and attach to centromeres, chromosomes line up across
equatorial plate

Anaphase

Chromatids segregate (separate) and move to opposite spindle poles

Telophase

Nuclear membrane reforms, chromosomes disappear, cytokinesis occurs

Asexual Reproduction (1 Parent Cell)

Nuclear division characterized by chromosome replication and formation of two identical
daughter nuclei (2n) using one division.

These cells are used for growth or replacement of dead or damaged cells.

Parent Cell (2n)=Daughter Cell(2n)

Karyeokinesis

Meiosis

Undergone by Germ cells (Gametic Cells)

Meiosis I (MI)

Reductional Division

Prophase I

Leptonema (Leptos = "Thin" nema="Thread)

Appear as long thing threads with many bead like structures

Zygonema (zygo="adjoining")

Synapsis or pairing of homologous chromosomes

2 Chromosome = Bivalent = 4 Chromatids

Pachynema (pachus="Thick")

Chromosomes are thicker due to further coiling

Crossing over

Repair may entail exchange of segments between sister and non sister chromatids in a bivalent

Cytologically observed throught the formation of chiasma (pl. Chiasmata) at the point of exchange

Nucleolus is still evident, the chromosomes attached to it are know as nucleolus organizers

Diplonema (Diplo="Two")

The synaptonemal complex no longer functional, the longitudinal seperation of homologues in a bivalent starts from the centromere and proceeds toward both ends except at the chiasma

Diakinesis (dia="Across")

Bivalents are maximally condensed and are distributed throughout the nucleus

Terminalization of the chiasmate between homologues that underwent crossing over occurs at this stage resulting in complete separation of the homologues

Metaphase I

Homologous chromosomes line up randomly on the equatorial plate,spindle fibers attach to the centromere

Anaphase I

Homologous chromosome pairs move to opposite poles of the cell in a process called segregation.

The chromatids do not separate at the centromere

Telophase I

Cytokinesis occurs forming two cells with half the number of chromosomes as the parent cell, nuclear membrane forms around the chromosomes

Meiosis II (MII)

Equational Division

Prophase II

Spindle fibers form, nuclear membrane disappears

Metaphase II

Chromosomes line up at equatorial plate, spindle fibers attach to centromeres

Anaphase II

Spindle fibers pull chromatids apart (breaks the centromere) and chromatids/chromosomes move to opposite poles of the cell

Telophase II

Nuclear membrane reforms around chromosomes, cytokinesis occurs producing two haploid cells from each cell.

Parent Cell(2n)≠Daughter Cell(n)

Meiosis is important because

It conserves the chromosome number in sexually reproducing species. Without it the number of chromosomes would be doubled every generation.

It continually reshuffles the genetic material (recombination) between generations producing natural variation.

Terms

Chromatin

Strands of genetic material (DNA) that are unraveled into long thin strands (accessible DNA) during interphase. Found during the resting phases of the cell’s life cycle

Chromosome

Thick shortened strands of genetic material (DNA) that is inaccessible or packaged. Noticeable just before cell division (condensed)

Chromatid

Replicated, identical chromosomes that are attached at the centromere. Chromatid pairs are found during cellular division (metaphase of mitosis and meiosis)

Homologous
Chromosomes

Chromosomes that contain similar genes or DNA sequences but are not identical. One of the pair comes from each parent.

Nucleolus

Used in the synthesis of ribosomes (protein synthesis)

Spindle fibers

Protein strands that attach to the centromere and pull the chromatids to opposite ends of the cell

Centriole

Found in animal cells only. They provide attachment for spindle fibers

Centromere

The spot, usually in the middle, . This spot holds the two sister chromatids together

Kinetochores

Site of attachement of spindle fibers

Diploid

two sets of chromosomes

Man=2n=46

Nucleus

Nuclear membrane

Nucleoli

one/Several small round bodies called chromatin

Chromatin

granular darkly staining material

Branch of Biology that studies heredity and variation

Heredity

transmission of traits from parents to offspring, similarity

Variation

differences between parents and offspring, differences among the offspring, difference among individuals in the population

Genes are the principal determinants of life processes

Organization of cells into tissues/organs

Cell Structure, Function

Organisms Appearance

Reproduction

Adaptability, Behavior

Three interrelated fields in genetics

Transmission Genetics (Classical Genetics) (Gregor Mendell)

- Encompasses the basic principles of genetics
- How traits are passed
- Discuss relationship between chromosomes and heredity
- How the individual inherits its genetic makeup and pass it to the next generation

Molecular Genetics

- Chemical nature of the gene
- How the genetic information is replicated, encoded, and expressed

Population Genetics

- Studies the genetic composition (frequency) of groups of individuals of the same species (population)
- How the composition changes overtime
- Study of evolution (genetic change)

Branches of Genetics

Molecular Genetics

- Physical Chemistry
- Biophysics
- Biochemistry

Cytogenetics

- Behavior of chromosomes (carriers of the genes)

- Physics(optics)
- Staining Technology

Developmental Genetics

- Gene regulation during development
- Switching on and off of genes

- Physiology
- Morpho-anatomy
- Biochemistry

Evolutionary Genetics

- Genetic change within and between species

- Ecology
- Math
- Statistics
- Biochemistry

Biochemical Genetics

- Role of enzymes/proteins
- Products of genes

- Biochemistry
- Physiology

Behavioral Genetics

- Traits that are inherited
- Product of genes
 Ex. Albanism=lack of Tyrosinase

- Psychology
- Biochemistry

Population Genetics

- Fate of genes in the population
- Factors affecting gene frequencies

- Ecology
- Math
- Statistics

Quantitative Genetics

- role of genetics and environmental factors
- inheritance and expression of quantitative traits controlled by the genes and highly affected by the environment

- Math
- Statistics

Application of genetics

1. Microbial, plant and animal improvement

- Genetic Engineering or Recombinant DNA Technology
- Genetically modified organism (GMO)
 Ex. Bt Corn, Cotton, Soybean, Eggplant
- Products of Recombinant DNA Technology
 Ex. Insulin, Dietary Control
- Norman Borlaug – Green revolution
pic

2. Medicine

- Identification of diseases and abnormalities (w/ genetic basis)
- Metabolic Disorders (Phenylketonuria, Galactosemia)
- Newborn Screening

Eugenics

- Coined by Francis Galton in1883 in England
- Application of genetic knowledge for the improvement of human race

3. Genetics Counseling

- Inheritance of undesirable traits
- Pedigree analysis of prospective patients

Euphenics

- Replaced Eugenics
- Medical and/or genetic prevention
- Designed to reduce the impact of defective genotyped on individuals

4. Legal Applications

- Blood Type analysis
- DNA finger printing
 Paternity testing
 Disputed Parentage
 Identify criminals

Greek Word “Gen” to become or grow into something, Coined by William Bateson in 1905

Beginnings of Genetics

Before Gregor Mendel

- Heredity was thought as blending process
- Offspring are intermediate between the parents (not true if offspring is similar to one of the parents

Golden age of Greek Culture attention was given to

- Reproduction
- Hereditary

Aristotle (Theory of Pangenesis)

- All structures and organs of the body contribute copies of themselves to sex cells

Jean Baptiste De Lamarck

- Theory of inheritance of acquired characteristic
- Acquired body modifications by use or disuse could be transmitted to the offspring’s

August Weismann (Germplasm Theory)

- Plans for the entire body are contributed only by the sex cells

Kolreuter, Gadner, Naudin, Charles Darwin and Dzierson

- Uniformity in f1
- Variations in f2

Beginnings of Classical Genetics

- 1865 Gregor Mendel (Father of Genetics)
- Concept of gene
- Presence of discrete hereditary unit
- Explains similarities and differences among parents and offspring’s
- Responsible for two important principles of genetics
i. Principle of Segregation
ii. Principle of independent assortment

Carl Correns (Germany), Erick Von Tschermack (Austria) and Hugo De Vries (Netherland)

- Duplicated Mendel’s experiment on plants

William Bateson, Saunders and Lucien Cuenot

- Observed Mendel’s principles on animal

Walter Sutton (USA) and Theodor Boveri (Germany)

- Chromosome theory of inheritance

Thomas Hunt Morgan and Calvin Bridges

- Association between specific gene and specific chromosome

Oswald Avery, Collin Mcleod and Maclyn Mccarty

- DNA as hereditary material

Elucidation of the DNA Structure

- 1953
- James D. Watson (Alive) and Francis H. Crick
- DNA double Helix

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Lecture 2

Introduction

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