Genetics and Heredity

Genetics and traits

• Genetics: the study of how certain features are passed from parents to their offspring

• Trait: a distinguishing quality that all members of a species have in common (eyes, chin, etc.)

• Variations: Different forms of the same trait (blue/brown/or green eyes, cleft chin)

Traits• Heredity: the passing of traits from

parents to offspring.• Heredity plus your environment will

work together to influence who you will become–“Nature Vs. Nurture

• Which do you think bear a greater impact on your development?

Reproduction and Heredity• Four basic methods of asexual reproduction:–1.Rooting: a cutting is taken from a mature

plant and rooted to create a new plant (often used to get desirable traits in agriculture)–2.Spores: like seeds can grow into new

organisms–3.Budding: small bud forms on the parent and

breaks off to form a new organism’–4.Fission: (most common) dna is copied, cell

divides, new cell membrane encases new daughter cells

Sexual Reproduction• Requires male and female cells (sperm and

egg) called gametes.• Does asexual or sexual reproduction generate

greater variety?• Sexual reproduction creates greater variety

due to a greater variety of trait possibilities.• Traits are passed from parent to offspring in

the form of genes• Genes: small segment of DNA that carries

hereditary info.

Genes

• Genes have all info needed to build, maintain, and reproduce an organism.

• Genes link together to form chromosomes• Organisms’ cells can read the codes in

chromosomes just like we read a book

Genetic Code

Genetic Code/Traits

• Some genes determine on trait:–Straight hairline or widow’s peak–Earlobes are attached or free

Heredity Recessive trait

Dominant trait

This woman’s genotype

This woman’s genotype

homozygousheterozygous

DNA

• http://www.youtube.com/watch?v=8kK2zwjRV0M

• DNA is a molecule shaped like a twisted ladder called a double helix• Sugar and phosphate make the

support/legs of the ladder• Nitrogen bases such as adenine (A),

thymine (T), guanine (G), and cytosine (C) are paired together to make the “rungs” of the ladder

• Nucleotide: the “rungs,” or the combination of bases• Certain nitrogen bases always pair

up:–A-> T–C->G

• Replication: The DNA strand unwinds, unzips, new nucleotides pair up with existing, exposed nitrogen bases and new sugar/phosphate support is produced.

Mutations

• Mutations are “errors” in genetic code• Seedless grapes are an example. • Mutation: a change in the sequence

of one or more nucleotides in a DNA molecule

• Substitution: Sickle Cell Anemia

• Insertion: Huntington’s disease

• Deletion: Cystic Fibrosis

• Inversion: Hemophilia

Mutations Cont• Some mutations do not effects the organism• Some affect appearance and health, some only one

of these• Some mutations are caused by a mistake in DNA

replication and take years to develop.• Some are uncontrollable, others are not• Mutagen is a physical or chemical agent that

causes mutations to occur• Radiation, smoke, chemicals, pesticides, drugs, x-

rays, ultraviolet light, radiation.

Chernobyl

• http://www.youtube.com/watch?v=IEmms6vn-p8