•Humans have 46 chromosomes

•Humans have 23 homologous pairs of chromosomes

•Chromosome pairs carry alleles for the same trait. We all have two alleles for each gene – one from each parent, 1 on each homologous pair

UNIT V

Sex chromosomes: In humans, females are XX and males are XY

• The Y chromosome is much smaller than the X, so males carry only a single gene for some traits. This makes the males more likely to have some traits (like color blindness).

• These are called sex-linked traits

While genes determine our traits, the environment can affect the expression of genes

Each chromosome has hundreds and thousands of genes

Each gene holds the code for a particular protein

REMEMBER: Genes carry the code to make

protein, but genes (DNA) are made of nucleic acids

DNA is made of 4 bases:

A T C G

The three letter codon represents a specific amino acid – these amino acids are assembled into proteins

Base pairs:

in DNA: A-T and C-G

in RNA: A-U and C-G

Changes to the DNA are called mutations. They can only be passed on if they are in the sex

(reproductive) cells (egg or sperm)Common mutagenic agents include

Radiation Chemicals Viruses

Mutations may cause a change in the structure of the protein coded for by a gene. This will have an effect on the way the protein works (if it works at all).

All cells in the body have the same genes (DNA).

Only some genes are turned on.

We are not sure yet why this happens

1. Selective breeding: produces plants and animals with desired traits (disease resistant, larger fruit, leaner meat, more milk, specific colors)

2. Genetic engineering or gene splicing: inserts the genes of one organism into the genes of another. Restriction enzymes are used to cut the DNA segments.

3. Bacteria are often used because they have no nucleus protecting their DNA and they reproduce very quickly.

Karyotyping

Gel Electrophoresis

UNIT VI

Modern species evolved from earlier species and share a common ancestor

Charles Darwin proposed that natural selection is the mechanism that causes change. The basic steps in natural selection are:

1. Overproduction of offspring. Offspring have variation.

2. Competition for limited resources. Variation affects the outcome of competition.

3. Survival and passing on genes or death and no passing on of genes

4. Variations that are beneficial are passed on and become more common. Variations that are harmful become less common because they are not passed on.

“Survival of the Fittest”

Better adapted organisms are more likely to survive and pass their genes on.

Less adapted organisms usually die and do not pass their genes on.

Better adapted (more fit) organisms are not always stronger, they are just better adapted to the environment

Species that cannot adapt to their environment become extinct.

Animals die – species become extinct

Species do not evolve because they need to, they just have variations that are favorable, and those variations continue on (evolve).

Variations exist as a result of sexual reproduction and mutations.

Species with more variations are better able to survive environmental change than those with little diversity.

PUNCTUATED EQUILIBRIUM: evolution occurred in quick bursts

GRADUALISM: evolutionary change occurs slowly

Creation of a new species usually requires geographic isolation. Geographic isolation eventually results in reproductive isolation.

Evidence in support of evolution comes from the fields of:

1. Geology (fossils and radioactive dating)

2. Genetics

3. Biochemistry

4. Anatomy (homologous and analogous structures)

5. Embryology

KINGDOMS are large groups of related organisms (bacteria, protists, animals, plants)

SPECIES are able to successfully reproduce amongst its members

Branching tree diagrams show evolutionary relationships

ECOLOGYECOLOGYUNIT VIIUNIT VII

Understand how organisms interact with their environment

FOOD WEBFOOD CHAIN

ECOLOGYECOLOGYUnderstand how organisms interact with their

environment

THE NITROGEN CYCLE

ECOLOGYECOLOGYUnderstand how organisms interact with their

environment

THE CARBON CYCLE

ECOLOGYECOLOGYUnderstand how organisms interact with their

environment

THE WATER CYCLE

ENERGY

Energy is needed to keep an ecosystem going. Energy comes from the sun and is made usable by producers (plants/autotrophes)

Energy is passed on to other organisms in the form of food

ENERGYSince all organisms must

use energy for their own needs, most energy is lost before it can be passed to the next step in the food chain. As a result, organisms high on the food chain have less energy available to them and must have smaller populations.

ENVIRONMENTAL FACTORS

Environmental factors determine which organisms can live in an ecosystem and how large the populations can get.

Air Water Temperature pH Food Predators

Carrying Capacity

The maximum size of a population is called the carrying capacity

ECOSYSTEM NICHES

There many roles in an ecosystem (niche), but competition between species usually results in only one species occupying a niche at any one time. Often organisms with similar needs will divide resources to reduce competition.

Example: Birds eat insects during the day and bats eat insects at night.

ECOLOGICAL SUCCESSION

Ecology Vocabulary

1. Producer: an organism, usually a plant, that can produce its own food

2. Consumer: an organism, usually an animal, that feeds on plants or other animals

3. Omnivore: an animal whose normal diet includes both plants and animals

4. Herbivore: an animal that feeds chiefly on plants 5. Carnivore: an animal that feeds chiefly on meat6. Predator: an organism that lives by preying on other

organisms 7. Parasite: an organism that grows, feeds, and is

sheltered on or in a different organism while contributing nothing to the survival of its host

8. Habitat: the natural home of an animal or plant

Ecology Vocabulary

9. Niche: the position or function of an organism in a community of plants and animals

10. Population: all the organisms that constitute a specific group or occur in a specified habitat

11. Community: a group of plants and animals living and interacting with one another in a specific region under relatively similar environmental conditions

12. Ecosystem: a system formed by the interaction of a community of organisms with their physical environment 

13. Biosphere: the part of the earth's crust, waters, and atmosphere that supports life

14. Pollution: the introduction of harmful substances or products into the environment

15. Renewable resource: any natural resource that can replenish itself naturally over time, as wood or solar energy

HUMAN ECOLOGY

Human action often has negative consequences for the ecosystem and humans, too!

Development Industrialization Over harvesting Over hunting Introduction of foreign species Soil erosion

Introduction of foreign species

1. Plants1. Purple Loosestrife

2. Garlic Mustard

Animals Round goby Zebra Mussel

Common foreign species in New York State:

The negative effects human’s have had on the environment are mostly attributed to the increasing human population causing

1. Acid rain : the burning of fossil fuels, such as coal, to produce electricity. In addition, the exhaust from cars, trucks, and buses releases nitrogen oxides and sulfur dioxide into the air. These pollutants cause acid rain.

2. Loss of habitat: as more and more people move to the cities, urban sprawl replaces natural habitats. The habitats that remain are fragmented and depleted.

3. Loss of diversity: loss of habitats lead to loss of diversity

4. Loss of ozone: the over use of chloroflourocarbon (CFC) compounds has led to the destruction of the layer over the earth that protects us from harmful UV rays (this has led to an increase in skin cancers)

5. Global warming: Is the increase in the average temperature of the Earth's near-surface air and oceans

6. Introduced species: when natural species are threatened by the invasion of exotic plants and animals

7. Industrialization: rapid industrial growth and vehicle exhausts has made water pollution, air pollution, and hazardous wastes pressing environmental problems in many areas of the developing world

The negative effects human’s have had on the environment are mostly attributed to the increasing human population

causing

Actions being taken by humans to reduce or repair damage to the environment

1. Recycling wastes

2. Conservation of resources

3. Using renewable resources (solar, wind, water)

4. Protection of habitats

5. Use of biological controls instead of pesticides and herbicides

6. Farming native plants (favorable to the environment)

7. Planting trees to replace those cut down

8. Rotating crops or planting cover crops to reduce erosion

9. Passing laws to control pollution, land management, hunting, and fishing

BIODIVERSITY Refers to the variety of life on earth As habitats and are lost and species become

extinct, biodiversity is reduced Ecosystems with low diversity are less stable

than ecosystems with more diversity Ecosystems with low diversity take longer to

recover from environmental changes We use organisms for many things such as

food and medicine; by reducing biodiversity we are losing potentially valuable resources