Bi 140 science, technology and society module 4

Genetic Inheritance

Module 4, BI 140

Contents

• Heredity and cell division

• Basic genetics

• Genetics in biotechnology

Heredity

• Heredity is the transmission of traits from parents to offspring

http://messybeast.com/mosaicism.htm

Heredity

• In sexual reproduction, half (or roughly half at least) of genes comes from a father and the other half come from a mother

– Human, animals, plants

• Asexual reproduction, all of the genes come from a single parent

– Bacteria, fungi, plants

Heredity

• Some traits are directly from one parent (egsex) and some traits are a mixture from both parents (eg skin color).

• Using Mendelian genetics, traits of offspring can be predicted using statistics.

Cell division - Mitosis

• Mitosis - the cell creates an exact copy of itself.

– Results in cells with the same number of chromosomes as the parent cell

http://techhydra.com/wp-content/uploads/cell-division-full.jpg

Cell division - Meiosis

• Meiosis - the cell divides to create gametes (egg or sperm) used for sexual reproduction

– Results in cells with half the number of chromosomes as the parent cell

– Cross-over is the transfer of genes from one chromosome to another. Cross-over only occurs during meiosis

Chromosomes

Chromosomes are condensed DNA (genes)

Chromosomes are visible under a microscope during cell division

Basic Genetics

• Genes code for proteins and proteins influence traits

• All living things contain genes. Viruses also contain genes.

– Humans have ~20,000 genes

– Ebola has ~7 genes

• Genes have variants (small changes) which can cause major or minor changes to the protein it codes for

Gene Expression

• Genes need to be expressed to create a protein

– Just because you have a gene does not necessarily mean that gene is going to be expressed

– Many “genes” in the human genome are never expressed

http://www.extremetech.com/ext

reme/134672-harvard-cracks-

dna-storage-crams-700-

terabytes-of-data-into-a-single-

gram

Traits

• Traits (characteristics of an organism) are a result of many factors including protein and nucleic acid activities

• The more “complex” the trait, the more complicated the genetics

• Consider twins. Twins have the same genome and very similar traits; yet they are still unique. This is because traits are a result of environment and experiences during life.

Environment

• Phenotypic plasticity – the degree to which a certain trait is affected by environmental factors

• Environmental factors influence gene expression and vice versa

– Food, water, air

– Parents, peers, other people

– Memories from all senses: visual, auditory, physical, etc.

– Physical activities, choices, etc

Mutations

• A change in the single or a few amino acids in a protein is called a mutation (also can be called a variant)

• A mutation or variant may or may not alter the structure or function of the protein

• A “bad” mutation can result in a disease (Sickle Cell Anemia or certain cancers)

• A “good” mutation can result in beneficial traits

Human Genome

• For humans, there are billions of base-pairs (A, C, T, Gs) in the human genome and (maybe) ~26,000 genes that are actually expressed.

• Each of these genes can have a number of variants and different expression patterns.

• The combination of genetics and experiences is what makes each person unique.

Genetics in Biotechnology

• Three growing fields in biotechnology

– Bioinformatics

– Computational Biology

– Systems Biology

• These fields conduct research in support of:

– Clinical/medical research

– Biopharmaceutical discoveries and development

– Evolutionary biology

– Forensic biology

– Engineering

Bioinformatics

• The use of information technology (computers, servers, etc) to study biology.

– Genetic and protein databases

– Software development for analysis and comparison of gene and protein sequences

• Finding variants/mutations in genes and proteins

• Evolutionary biology

Computational Biology

• Using computers to model, visualize, predict, simulate biological processes.

– Predict protein sequences

– Visualization of protein folding

– Predict protein interactions with chemicals

http://www.mdpi.com/1422-0067/14/8/16882

Systems Biology

• Determining the molecular function of a protein could predict what could happen if the protein changes

http://abeautifulwww.com/GeneVisualizatio

ns_E01C/cerebralmapk.jpg

• The study of biological systems - Systems biology attempts to define (the very complex) biological processes