Welcome to Human Heredity!

Heredity transmission of genetic factors from parents or ancestors to offspring or next generation

Genetics- the field of biology that studies heredity

Biological Themes (Learning Objectives)

1. Properties shared by all living organisms– The cell theory– The concept of emergent properties or emergence– Form or structure dictates function– DNA is the genetic material directing the functions of the cell.– Oder and balance

2. Unifying themes for the study of Biology– Levels of biologic organization of the living world in ascending

and descending fashion. – The importance of diversity for life on earth

3. New terminology

The cell Theory:

A cell is the basic unit of biological structure and function

All cells arise from preexisting cells

Two Types of cells on earth differ in size and complexity

– Eukaryotic (True…) cells:

– Prokaryotic (Before…) cells:

Nucleus(contains DNA)

Eukar yotic cell

Prokar yotic cell

DNA(no nucleus)

Organelles

25,0

00 ×

100 X

nucleuscytoplasm

Sperm cell

NucleicontainingDNA

Egg cell

Fertilized eggwith DNA fromboth parents

(Zygote)

Embyro’s cells with copies of inherited DNA

Offspring with traitsinherited fromboth parents

Human DevelopmentFrom single cells into a large multi-cellular organism

Unspecialized cells

Different specialized

cells

Cells• All cells of the body contain the same genetic material

• Differentiation causes cells to differ in appearance and function- Controlled by variation in gene expression

• Stem cells are less specialized and can become many different cell types

Emergent Properties

Biological systems are much more than the sum of their parts

Structure or form fits function at all levels of biological organization

Electronic information on CD

Sent to and recognized by CD Player

Music is produced

Genetic information

(DNA)

Visible feature or trait/color of a flower (protein)

Genetic material directs all the cell activities- Made of DNA (information)

- Must be replicated before the cell can divide

Gene expression

Genetic Material• DNA is organized inside the nucleus• Genes are the units of heredity made of segments of DNA• Genome all the DNA present in one cell

Reading1.1, Figure 1

DNA

Cell

Nucleotide

A

C

T

A

T

A

C

C

G

G

T

A

T

A

Nucleus

Two types of nucleic acids necessary for directing the activities of the cell

• DNA– One structure or shape …… one function

• RNA– Several shapes…… multiple functions

Deoxyribonucleic Acid (DNA)

• A double-stranded chain of units (deoxyribonucleotides)

• A polymer (made by connecting many)

• Each deoxyribonucleotide- Phosphate- Sugar: Deoxyribose- Bases: Adenine A

Guanine GThymine TCytosine C

Reading 1.1, Figure 2

Gene expression starts with the genetic material, DNA

1. Replicates before cells can divide

2. Directs the synthesis of proteins

The sequence of the bases code for the sequence of the building blocks, amino acids, of a protein

Ribonucleic Acid (RNA)

• A single stranded polymer of ribonucleotides• Ribonucleotide components:

- Phosphate- Sugar: Ribose- Base: Adenine A Guanine G

Uracil U Cytosine C

• Exists in several types

• Passes on the information and participates in directing the cells synthesis of proteins

Genetic variations• Form by mutation, changes at the DNA level

• Mutations in sperm or egg cells are passed on to the next generation

• Mutations may be positive, negative, or neutral

• Alleles are variants of genes

- Ascending vs. Descending fashion

- Each level builds on the level below it, leading to new emergent properties

- Biological systems are much more than the sum of their parts

Levels of biological organization

Atoms/Elements

Molecules

Organelle

Cell

Tissue

Organ

Organ system

Organism(Family)

Population

Community

Ecosystem

Biosphere

Chemical world

Biological W

orld

Non-living

Living

Ascending

Descending

The human body contains- About 50-100 trillion cells- 4 types of tissues- More than 260 types of cells

Levels of biologic organization

– Organism: a living individual

– Family: genetically connected Individuals

– Population: a localized group of individual organisms of a species. All alleles in a population is a “gene pool”

– Community: living organisms from different populations living together in one place

– Ecosystem: all living as well as the nonliving environmental components of a place

Evolutionary Adaptation of populations

– Genetic diversity along with external factors including natural selection lead to differential reproductive success.

– Populations change over long periods of time– Natural selection- Charles Darwin How evolution really workshttp://www.pbs.org/wgbh/evolution/library/11/2/e_s_4.html

1. A basic set of genes is shared by all living organisms

2. Mutations change DNA sequence

3. Mutations take place over time

4. Sequencing of genomes shows their evolutionary relatedness.

5. Closely related organisms have more similar genes.

Genome comparisons among species reveals evolutionary relationships- The more similar the sequences are, the more recent the divergence from a common ancestor

98% of human DNA sequences are shared with chimpanzees

Humans share genes with mice, pufferfish, fruit flies, yeast, and even bacteria

Evolution

Themes of Genetics (Learning Objectives)

1. The branches of biology concerned with heredity and variation

– Genetic fields of study: Classical (Mendelian patterns of inheritance) Molecular (from DNA to protein and its control)Effect on all levels of biological organization

– Genetic variability and factors affecting variability of gene expression– DNA technologies– Genomics: analysis of genomes and their variation– Genomic technologies

2. Impact of modern genomic and DNA technologies

Change of genetics from an academic science to a clinical science with practical and societal implications for

– Health, Research, Environment– Bioethics is a field of study concerned with issues of privacy, confidentiality, and

discrimination.

Genetic Variability• Single Gene Traits and multi-factorial traits

– No gene functions in isolation• Influenced by other genes• Environmental factors: life style, exercise, diet

– Risk prediction: severity of symptoms (variable)– Lead to differences in protein structure, level,

place, or time of expression

Is gene expression is influenced by nature, nurture, or both?

Common genetic variations

The human genome consists of 3 billion nucleotides only 1.5 % codes for proteins

Individual genetic variations– Single nucleotide polymorphism (SNPs)– Variable number of tandem repeats (VNTRs)– Insertions/Deletions (Indels)– Short Tandem Repeats (STRs)– Multinucleotide polymorphisms (MNPs)

Common genetic variationsSingle nucleotide polymorphism (SNPs)

• DNA sequences vary between individuals. • “Polymorphism” variation present in >1%

of the population• SNPs are spread across the genome• May be disease-causing or a marker of

variation.

Genome-wide Association Studies

1. SNP-based– Identification and tracking of combinations of

SNPs associated with certain traits– Predictive value to estimate risk of disease

2. RNA level-based– Gene expression profiling: level of RNA

Applications of Genetics and its Modern Technologies

• Identity studies (Forensics & Ancestry)• Screening for carriers of single-gene disease• Health Care (Pharmacogenomics)• Redefining Disease (Reflection of gene expression)• Genetic Testing (GINA Act value and limitations)• Agriculture (GM food and transgenic organisms)• Ecology (Metagenomics and the Microbiome project)• Global Efforts

Current Pharmacogenomic Tests

Disease as a Reflection of Gene Expression