Genetics Module 1

Why Study Genetics

Pivotal in ALL areas of biology

Integral part of human life

Four Properties of Information Passage

Diversity of structure

Ability to replicate

Mutability

Translation

Diversity in Structure

Variations in genetic sequences, levels of organization, and functional roles.

Ability to Replicate

The capability of genetic material to undergo duplication during cell division, ensuring that genetic information is passed on to daughter cells.

Mutability

The intrinsic property of genetic material that allows for changes or alterations in its sequence, contributing to evolution and adaptation.

Translation

The process by which ribosomes synthesize proteins by decoding messenger RNA (mRNA) sequences into amino acids.

Genes

The process by which the information encoded in a gene is used to synthesize a corresponding protein, involving messenger RNA and ribosomes.

Basic element of the system of inherited info (1909)

Genome

The complete set of genes or genetic material present in a cell or organism, encompassing all of its hereditary information.

Collection of all genes in an organism

Genetics

The study of genes, genetic variation, and heredity in living organisms. It encompasses various aspects of heredity, genetic diseases, and the mechanisms of gene expression.

Genotype

The genetic constitution of an individual, representing the specific alleles inherited from both parents that determine a particular trait.

Genetic/Allelic constitution of an organism (1 from mom, 1 from dad)

Phenotype

The observable physical or biochemical characteristics of an organism, determined by both its genotype and environmental influences.

Physical manifestation of a genotype (can see it/actually displayed)

3 Major topics of genetics

Transmission Genetics

Molecular Genetics

Population Genetics

Transmission Genetics

The branch of genetics that deals with the inheritance patterns of traits and how they are passed from one generation to the next, focusing on the roles of chromosomes and genes.

Inheritance of genes across generations

Molecular Genetics

The branch of genetics that studies the structure and function of genes at a molecular level, exploring how genes interact with each other and their role in the regulation of gene expression.

Gene expression

Population Genetics

The branch of genetics that deals with the distribution and changes in frequency of alleles within populations, focusing on genetic variation and evolutionary processes.

Genes in population

Genetics is…

The scientific study of heredity, variation, and the role of genes in biological inheritance.

Study of Genes

Gregor Mendel - Father of Genetics

What is a Gene

A basic unit of heredity in living organisms, consisting of DNA that encodes the information for building proteins and regulating various functions.

A “section” of deoxyribonucleic acid (DNA) that makes up a chromosome

Gene Locus

Gene Locus

The specific location or position of a gene on a chromosome, which determines the hereditary characteristics of an organism.

Big to Small genetics

Organism → Cells → DNA → Chromosome Pair → Functional Regions → DNA Double Helix

What do genes show

What males a species what it is

What causes variation within a species

What makes a species what it is?

Genes dictate the inherent properties of a species

Protein

Protein

Functional unit or product of a gene

What causes variation within a species?

Alleles

Mutations

Alleles

Different versions of a gene that determine specific traits in an organism.

Mutation

Change in DNA sequence

Rare, but evolutionarily conserved

Central Dogma

The fundamental principle that explains the flow of genetic information from DNA to RNA to protein.

DNA

Polymer of Nucleotides

Nucleotides made of 3 parts

2 types of Nitrogenous bases

Parts of the Nucleotide

Nitrogenous Base

• Adenine, Thymine, Cytosine, Guanine

Sugar

Phosphate

Types of Nitrogenous Bases

Purines (A and G)

Pyrimidines (C and T)

Structure of DNA

Double Helix

dNTPs connected by a phosphodiester bond

Phosphate sugar backbone

Held together by H bonds

• G to C (triple bond)

• A to T (double bond)

Turns to the Right

• Runs 5’ to 3’

• Major Groove

• Minor Groove

Major Groove

The larger of the two grooves in the DNA double helix, allowing for the binding of proteins and regulatory factors. It provides access to the bases for interaction with molecules such as transcription factors.

Minor Groove

The smaller of the two grooves in the DNA double helix, allowing access for regulatory proteins and other molecules.

Runs 5’ to 3’

Describes the orientation of the DNA strand where the 5' end of the sugar is at one end and the 3' end at the other, indicating the direction of DNA synthesis and elongation.

DNA Replication

The process by which a DNA molecule makes a copy of itself, ensuring that each daughter cell receives an identical set of genetic information. This process involves unwinding the double helix and synthesizing a new complementary strand.

RNA Transcription

The process by which messenger RNA (mRNA) is synthesized from a DNA template, allowing for the transfer of genetic information from DNA to RNA.

Catalyzed by RNA Polymerase

Synthesized 3’ to 5’

Protein Translation

The process by which ribosomes synthesize proteins using messenger RNA (mRNA) as a template. During translation, transfer RNA (tRNA) brings amino acids to the ribosome, where they are assembled into a polypeptide chain.

Flow of Information and Differences from Eukaryotes and Prokaryotes

The flow of information in cells refers to the transfer of genetic information from DNA to RNA (transcription) and then to proteins (translation). In eukaryotes, this occurs with compartmentalization in the nucleus and cytoplasm, while in prokaryotes, it happens concurrently in the cytoplasm due to the lack of a defined nucleus.

Genome

The complete set of genetic material present in an organism, including both the genes and non-coding sequences within the DNA.

Basic complement of DNA

Haploid

Diploid

Haploid

A cell that contains half the number of chromosomes as a diploid cell, typically seen in gametes such as sperm and eggs.

Diploid

A cell or organism that contains two complete sets of chromosomes, one from each parent, resulting in a total of two copies of each gene.

Dominance

One Allele can express the phenotypic effect regardless of other allele

Recessiveness

Need 2 copies of an allele to express the phenotypic effect

Homozygous

Two copies of the same Allele

Heterozygous

One copy of two different Alleles

Genetic Variation (2 types)

Continuous

Discontinuous

Continuous

Unbroken Range of Phenotypes (height)

Discontinuous

2 or more distinct phenotypes found in population (blood types + finger print types)

Discontinuous Variation (2 types)

Polymorphism

• Originally comes as a mutation

Mutation

Polymorphism

Several phenotypes associated with alleles of one gene

Common

Mutation

Process that produces a gene different from the wild type

• “Wild type” - “Normal” phenotype

• Mutant - other than wild type

• Rare and Spontaneous

Forward Genetics

Genetic investigation begins with an observation variant phenotype - See change → Find gene

Searches for the genetic differences underlying variation

Wild type = normal form

Mutant = variant form

Punnet Square

A diagram used to predict the genetic outcomes of a cross between two individuals, illustrating all possible allele combinations.

Line Branch

A graphical representation used to predict the genetic makeup of offspring from a cross between two organisms. It shows the possible combinations of alleles from the parents.

Reverse Genetics

A method that starts with a known gene and aims to determine its function by analyzing the phenotypic effects of targeted gene manipulation, such as knockout or transgenic approaches.

Starts with normal DNA and mutate it

Compare Genome to related species

Methodologies

applied in genetics to study gene functions and interactions, often involving techniques like gene editing or sequencing.

Isolation of mutations affecting the biological processes under study

Analysis of progeny of controlled matings between wild-types and mutants

Analysis of cell’s biochemical processes

Microscopic analysis

Direct DNA analysis

Genetic Techniques

Agarose gel electrophoresis

Whole gene sequencing

PCR

Rt-PCR

Western Blotting Workflow

Model Organisms

Biological species used to study genetic functions and processes, providing insights that are often applicable to other organisms. Examples include mice, fruit flies, and yeast.

Chosen for their properties, small size, short lifespan, easy to culture/mate

Viruses

Microscopic agents that can infect living organisms, composed of genetic material surrounded by a protein coat. Used in genetic studies to understand gene transfer and interactions.

Nonliving

Infect host cell to produce more

Bacteriophage

Used to study physical and chemical DNA structure and mechanics of DNA replication and mutation

Bacteriophage

A type of virus that specifically infects bacteria, used extensively in molecular biology to manipulate genetic material and study DNA replication. They serve as tools in genetic engineering and gene therapy.

Prokaryotes

Organisms without a membrane-bound nucleus, including bacteria and archaea. They are characterized by their simple cell structure, lacking organelles found in eukaryotic cells.

Single-celled and no nucleus

Haploid

Ex. E.Coli

Escherichia coli

A common species of bacteria in the intestinal tract of humans and animals, often used as a model organism in molecular biology and genetics. It has a simple, well-studied genome and is utilized in biotechnology and research.

Yeast

A eukaryotic microorganism used in fermentation and as a model organism in genetics and cell biology.

Single-celled fungi

A sexual and sexual reproduction

Saccharomyces cerevisiae

Saccharomyces cerevisiae

A species of yeast widely used in baking, brewing, and scientific research due to its rapid growth and uncomplicated genetic makeup.

Filamentous fungi

A group of fungi characterized by long, thread-like structures called hyphae. They play important roles in decomposition and are also used in food production and antibiotics.

Have filaments for nuclear division

Fruiting body

Neurospora

Neurospora

A genus of filamentous fungi widely studied as a model organism in genetics for its simple genetic structure and ease of manipulation.

Multicellular Organisms

Organisms composed of multiple cells that are organized into specialized structures and perform various functions, such as plants and animals.

Differentiation of cells, tissue and organs

Development of body form

Must be easy to culture, short life cycle, and large # of offspring

Arabidopsis thaliana

A small flowering plant related to cabbage and mustard, commonly used as a model organism in plant genetics due to its simple genome and short life cycle.

Small genome - 5 chromosomes

Studied and compared to animal plants

Drosophila melanogaster

A species of fly, commonly known as the fruit fly, widely used as a model organism in genetics due to its fast reproduction, well-mapped genome, and the ease of observing genetic variations.

4 chromosomes

Most used organism

Compares invertebrates and vertebrates

Caenorhabditis elegans

A free-living nematode, commonly known as the roundworm, used as a model organism in biology for studies of development, neurobiology, and genetics due to its simple anatomy and transparent body.

Few thousand adult cells

Nervous, digestive, and reproductive system

Mus musculus

Commonly known as the house mouse, it is a widely used model organism in genetics and biomedical research due to its genetic similarity to humans, rapid reproduction, and ability to be kept in a laboratory setting.

Model organism for vertebrates

Multiple uses

Genes, Environment, and Development Noise

The final phenotype of an organism is determined by the genotype, environment and developmental variation

Genetics and Evolution

Charles Darwin and Alfred Russel Wallace

• Similarities are due to common ancestry

• Differences are due to the force of natural selection in different habitats

• Natural Selection

Natural Selection

The process whereby organisms better adapted to their environment tend to survive and produce more offspring. This mechanism is a key driver of evolution.

Evolution

Natural selection acting on variation

Widely accepted

Driving force is genetic change

No such thing as micro or macroevolution

Genetics has made the largest contribution to evolution