Living OrganismsSome basic characteristics of life:

Need

NUTRIENTS

Need H2O

GAS GAS EXCHANGEEXCHANGE

Made of

CELLS REPRODUCE

Living OrganismsSome basic characteristics of life:

All living things need H2O

Living OrganismsSome basic characteristics of life:

Living things Need

NUTRIENTS

Living OrganismsSome basic characteristics of life:

Living things have Living things have a system fora system for

GAS GAS EXCHANGEEXCHANGE

Living OrganismsSome basic characteristics of life:

Made of

CELLS

Living OrganismsSome basic characteristics of life:

All living things REPRODUCE

ASEXUALLYASEXUALLY

to create new individuals that are clonesclones

SEXUALLYSEXUALLY

to create new individualswith a combination of traitscombination of traits

• Only one parent reproduces.• The same genetic material (DNA) is

passed directly from parent to offspring.

• All offspring are CLONES of the parent and have the exact same traits.

ASEXUALASEXUAL REPRODUCTION

Types of Asexual Types of Asexual ReproductionReproduction

• FissionCell division by a parent cell splitting into two parts, each growing into a new exact copy of the parent cell.

• Budding To develop as a growth on a parent, then break off

and mature into a new exact copy of the parent.

• Fragmentation and Regeneration Offspring can grow from a fragment (piece) of the

parent, or the parent can re-generate the missing piece.

FISSION

FISSION

BUDDING

Planarians are flat worms

that can be rapidly regenerate.

They can be cut across or along

their body.

Fragmentation

Regeneration

• Two parents (of opposite sex) reproduce.• Two sex cells (one from each parent)

combine during fertilization.• Parents combine genetic material (DNA)

to form offspring that has a COMBINATION of parent’s traits.

SEXUALSEXUAL REPRODUCTION

Egg

23 X

Sperm23 x

zygote46 X

Contains half of the

mother’s DNA

Contains half of the

father’s DNA

Mothers half + fathers half

= Full set of DNA

Female cell divides to produce

eggs

Male cell divides to produce

sperm

Genes and Chromosomes

GENES and GENES and CHROMOSOMESCHROMOSOMES

• Inside the cell nucleus are chromosomes.

• Chromosomes are bundles of tightly coiled strands of long molecules called DNA.

• A segment of DNA codes for a trait.• These segments are called GENES.

A gene codes for a specific type of trait.

Each trait isdetermined by

a pair ofGENES.

A chromosome is a bundle of DNA.Segments of DNA are genes.

Gregor MendelGregor Mendel

-Austrian Monk-Gardener/Scientist-Worked with peas-Noticed patterns of traits in generations-Developed the main idea of heredity

Gregor Mendeldetermined that…

• Each trait is determined by a pair of genes – one from each parent.• Both parents contribute equally to your genes.• A gene is either dominant or recessive.

• Three possible gene pairs for any trait: 2 dominant genes2 recessive genes1 dom and 1 rec gene

Dominant Genes

• Dominant genes are ‘stronger’ than recessive genes, and can cover them up.

• If at least one gene in the gene pair is dominant, then the individual will ‘express’ the dominant form of the trait.

• Represented with a CAPITAL letter… Usually the first letter of the trait.

• Ex: Black fur is dominant, so B = a dominant gene.

Recessive Genes

• Recessive genes are weaker, and cannot cover up dominant genes.

• ONLY if both genes in the gene pair are recessive, then the individual will ‘express’ the recessive form of the trait.

• Represented with a lower case letter.. Usually the first letter of the trait.

• Ex: Black fur is dominant, white fur is recessive, so b = a recessive gene.

Genotypes and PhenotypesPossible gene combinations

Genotype Phenotype

2 dominant genes

AAPurebred dominant

Dominant trait expressed

1 dominant gene and 1 recessive gene

AaHybrid

Dominant trait expressed

2 recessive genes

aaPurebred recessive

Recessive trait expressed

Gregor MendelGregor Mendel studied many traits of pea plants, like seed color and shape, and the color of the petals.

Traits in Humans Dominant

Recessive • Brown eyes• farsightedness• normal vision• normal vision• normal vision• Dimples• unattached

earlobes• Freckles• broad lips

• Gray, blue, green, hazel

• normal vision• Nearsightedness• night blindness• color blindness*• no dimples• attached earlobes• no freckles• thin lips

Practice Questions

DIMPLES ARE DOMINANT OVER DIMPLE-LESSNESS.

What is the genotype of someone who has no dimples?

What is the phenotype of someone who has a genotype of Dd?

dd

They have dimples.

Practice Questions

CURLY HAIR IS DOMINANT OVER STRAIT.

What is the genotype of someone who has curly hair?

What is the phenotype of someone who has a genotype of cc?

CC or Cc

They have straight hair.

Practice Questions

Which of the gene pairs are:

Purebred dominant?

Hybrid?

Purebred recessive?

Aa BB

Cc dd

ee FF

Gg hh