ibrahim bio notes

Methicillin - Resistant Staphylococcus aureus

• Infectious bacterium

• Difficult to treat with antibiotics 

• Killed 10,000 people in the united states in 2012

Staph Infection

• S. aureus (also known as staph)

• Some strains are harmless, whereas others cause disease

• Drug resistant strains exist

• Approximately 2% of the U.S. population has MRSA strand

• Approximately 33% of the U.S population has S. aureus.

• Most of these individuals are buttcha ha

Antibiotics

• Beta-lactams work by interfering with bacterias ability to make cell wall

• Antibiotic interfere with the function of essential bacterial cell structures

Bacterial Reproduction and Mutation

Binary fission: one parent cell divides into two daughter cells

Binary fission occurs quickly, but each time it causes some changes to DNA.

Antibiotic resistance

• Random mutations can create new alleles that cause some bacteria to be resistant to antibiotic

• Gene transfer can spread alleles for antibiotic resistance to other bacteria 

Jean Baptiste de Lamarck (1744-1829)

• French

• Theory of acquired characteristics

• Theory of disuse

DAY 2

Adaptations are often compromises - not about ‘perfecting’ organisms

Chance, natural selection and the environment interact

Adaptive radiation is when they drive rapidly  into a multitude of new forms, typically happening with a big change in the environment.

The variety in any generation may be insufficient for survival, particularly during periods of relatively fast environmental change.

Founder Effect= A random change in allele frequencies from the parents population that occurs when a small founding group establishes a new population

Genetic drift= random chance events

Mutation= Any change in the hereditary material (DNA) of an organism.

Natural selection - the process by which individuals with certain heritable traits tend to produce more surviving offspring than individuals without those traits. This lead to a change in the allele frequency of the population

Fertile= can create offspring

For a population to evolve, something must act on the gene pool to change how often a particular allele is present in the population.

The bottleneck effect leads to a loss of genetic diversity when population is greatly reduced.

Gene flow

• Is the movement of individuals or gametes/spores between populations and

• Can alter allele frequencies in a population

• To counteract the lack of genetic diversity in the remaining illinois greater prairie chickens,

• Researchers added 271 birds from neighborhood states to the illinois populations, which

• Successfully introduced new alleles

DAY 3

For a population to evolve something must act on the gene pool to change how often  particular allele is present in the population.

The three main causes of evolutionary change are

-Natural selection

-Genetic drift

-Gene flow

-If individuals differ in their survival and reproductive success, natural selection will alter allele frequencies.

Stabilizing selection favors intermediate phenotypes, acting against extreme phenotypes

Directional selection acts against individuals at one of the phenotypic extremes.

Disruptive selection favors individuals at both extremes of the phenotypic 

A species

range.mating

Share features

Microevolution is evolutions smallest scale 

Changes in the gene pool from one generation to the next

When speciation occurs one species splits into 10 sir

They share many characteristics

Population with varied inherited traits → Elimination of individuals with certain traits and reproduction survivors.

The biological species concept

Reproductive isolation vs gene flow

Production of fertile offspring

DAY 4

The three main causes of evolutionary change are 

Natural selection

Genetic drift 

Gene flow

Urbanization can prevent gene flow and lead to inbreeding

Inbreeding depression

Closely related individuals are more likely to share the same alleles

Negative reproductive consequences for a population

Associated with high frequency of homozygous individuals possessing harmful recessive alleles

For a population to evolve, something must act on the gene pool to change how often a particular allele is present in the population.

Primates had evolved as small arboreal mammals by 65 million years ago. 

Primates include 

-Limber joints

-Grasping hands and feet with flexible digits

-a short snout

-Forward pointing eyes that enhance depth perception 

The human story begins with out primate heritage

A phylogenetic tree shows that all primates are divided into three groups:

 Lemurs, lorises, amd bush babies

Tarsiers, and

Anthropoids, including monkeys and apes.

Most apes do not have a tail and most have long arms and short legs

Monkeys have forelimbs that are about the same length as their hind limbs

Hominins include modern humans and their extinct relatives.

Hominids include all those and gorillas and orangutans and other monkeys

Paleoanthropology, the study of humans origins and evolution

australopithecus 

2.6 million years ago

Could walk up right

Lived on the ground

Tools

Bipedal: spine connects to bottom of skull and can walk up right

Bipedalism precedes larger brain size

Chimpanbutt and gorillas knuckle walk

Walked upright before big brain

All living humans have ancestors that originated as homo sapiens in africa. 

Oldest known fossils with the definitive characteristics of our own species were discovered in Ethiopia and are 160,000 and 195,000 years old

Evidence from fossils and DNA studies has enabled scientists to trace early human history.

The oldest human populations are in Africa

A series of migration events from the original population in Africa gave rise to all the other human populations. 

Humans evolved in Africa

-Humans originated in africa aproxx 200,000 to 300,000 years ago

-A group migrated

To further study the out of Africa hypothesis, scientists study mitochondrial DNA (mtDNA)

-mtDNA is inherited solely from mothers.

mtDNA mutates at a regular rate.

We can track human ancestry and build an evolutionary tree “mitochondrial eve”

A mother with a mutation in her mtDNA will pass it to all her children

We can track human ancestry and build an evolutionary tree

Humans are genetically similar

Homo sapiens: biological species of human

Highly similar to one another

SKin tone in humans

Skin tone reflects levels of melanin

-Pigment produced by a type of skin cell

Skin tone correlates to geography

Melanin absorbs uv light

Some nutrients are affected by uv light

Folate and Vitamin D

Essential and impacted by sunlight exposure:

Folate

Destroyed by UV light in skinli

Needed for proper development

Low folate + birth defects

Vitamin D

Produced when skin exposed to UV light

Needed for immune system, bones, teeth

Low vitamin D = premature birth, rickets, neurological disease

Natural selection in skin color

Positive selection tends to make trait more common

Skin color correlates with geography

DAY IDK

The abiotic factors of the biosphere are not static

Study: track wolves and moose for many years to understand how these populations are linked

Ecology: the study of interactions

• Among organisms

• Between organisms and their nonliving environment

• Ecology can focus on

• Community: interacting populations of different species in a defined habitat

• Ecosystem: all the living organisms in an area and the nonliving parts of the environment with which they interact

Distribution patterns

• Clumped distribution: when resources are unevenly distributed across the landscape

• Or when social behavior dictates grouping

• Examples: wolves, schools of fish

Uniform distribution

• Results from territorial behavior

• Examples:

• Penguins often spread out evenly

• Some plants produce toxins that prevent seedlings from establishing too close to them.

There have not always been wolves or moose on Isle Royale

Moose in 1900: abundant food, no predators

Two wolves in 1950

Growth rate

Immigration vs emigration

Population size

Logistic growth

Starts off fast

Levels off due to environmental factors that limit ability to reproduce

Carrying capacity

-maximum number of individuals an environment can support, given its space and resources

-Often depends on availability habitat: the physical environment in which an animal l

Population interactions

Anything that affect the size of one population could also affect the size of other populations in the ecosystem

Isle royale

The wolf population increases and decreases depending on availability of food( moose)

The moose population increases and decrease depending on predation on predation from wolves and availability of food (leaves from trees)

Tree growth depends on foraging by moose.

Factors affecting populations

Density-independent factors

-a factor influences population size and growth regardless of the number and crowding within a population

Example: weather

Density-dependent factors

-A factor that influences population size and growth depending on the number and crowding of individuals in the population

Example would be predation

There were once approximately 30 million bison in North america.

By the late 1800s, they had been hunted down to 500 individuals

Due to conservation efforts, there are now 500,000 bison, mostly on ranches.

The American Prairie Reserve (APR) is a rewilding effort to restore 3.2 million acres of land. Rewilding: restoring native wildlife to their original habitat

Apr consists of existing public land, plus land purchased by private donors

If completed, APR would have the largest bison herd in the world.

Prairies are also excellent for cattle

APR is controversial for some, especially ranchers who think of it as a challenge to their way of life.

Cattle do not wallow or roam wildly, so they do not have the same positive influence for other species as bison

APR is controversial for  some, especially ranchers who think of it as a way to challenge their way of life.

An ecosystem is all the lift and all the nonliving things and processes in an area.
This American prairie is one example of an ecosystem.

Role of species in ecosystem 

Some species play particularly important roles in ecosystem: keystone species

Bison are considered a keystone species because they are particularly important to their prairie ecosystems

Examples of keystone species:

Prairie dogs

Elephants

Hummingbirds

Bison

Wolf

Bees

Sharks

Role of species in ecosystems

Bison grazing promotes the growth of plants other than grass

Without bison, grass overgrowth crowds out other plants

Without bison, many other animal species lose habitat and become less common holmes.

Some species are ecosystem engineers-keystone species that alter habitat for other species

Climate often determines the distributions of communities

Uneven heating of earth's surface

• Patterns of precipitation

• Prevailing winds

Biomes:

Aquatic

-salinity

-freshwater

Terrestrial

-temperature

-precipitation

Biomes 1 of 2

biomes : large areas defined by characteristics plant life

Terrestrial (land) biomes: Plant life is driven by patterns of temperature, rainfall, and seasons

Freshwater biomes: Standing water biomes (lakes and ponds) and

2 flowing water biomes (rivers and stream)

Tundra: arctic and mountain regions:

-low growing vegetation

-layer of permafrost soil, frozen all year long, close to the surface of the soil

Taig: evergreen trees

Long and cold winters, only short summers

Temperate deciduous forest: moderate winters and rainfall

Trees (evergreen or deciduous) drop their leaves in the winter

Temperate grassland: perennial grasses and other non woody plants

-In north america, prairies are examples of grasslands

Mediterranean: Long hot dry summers and cool damp winters

-short evergreen trees and shrubs with leathery leaves are found here

Six major elements - H, C, N, O, S and P- constitute the major building blocks for all biological macromolecules