AP Biology

Cell Specialization

• During development an organisms cells differentiate from Stem cells

• Stem cell – any unspecialized cell that can produce, during a single division one identical daughter cell and one more specialized daughter cell

• This occurs via structural and functional divergence of cells

Cellular organization

1. Molecular level (chemicals)

2. Cell

3. Tissue

4. Organ

5. Organ system

6. Organism

Form and Function

Homeostasis

Feedback

Environment

Disruption

Abiotic Biotic

Response

Behavioral • Timing and

coordination of events

Physiological • Defense • Development

Positive and Negative feedback

• Negative – Reduces frequency, regulates physiological processes back to a target set point (long term)

• Positive – Increase frequency or amplify processes (short term)

Target set point

Negative feedback

Stabilization

Temperature regulation

Plant responses to water

Positive feedback

Amplification

Fruit ripening Lactation in mammals

Child birth

Temp. regulation

Regulator

Vs

Conformer

To become attractive plants produce fruit, this makes them desirable so animals will take and carry off their seeds.

Plants communicate via ethylene – a gas

Other Positives

• Lactation in mammals – When baby drinks milk, hormones prolactin and oxytocin are released, this causes milk to be released and produced.

• Child birth – pressure on cervix causes contractions. Contractions cause more pressure

• Blood clotting – vascular spasms

Decrease blood flow, plug

formation, coagulation

Alteration of feedback

• Some changes to homeostasis are regulated and many are controlled by hormones.• Examples:• Women’s menstrual cycle• Circadian rhythm (changes that occur every 24 hours) • Acclimation- gradual process in which animal adjusts to

external environment

Normal alterations

Maintaining homeostasis physiological

• Thermoregulation – process by which animals maintain an internal temperature

• Endothermic – warmed by heat they generate via metabolism

• Ectothermic – gain heat via external sources

Maintaining homeostasis

• Balancing Heat Loss and gain

• Integumentary system• Insulation • Circulatory adaptations • Cooling via evaporative heat loss

Maintaining homeostasis

• Increases blood flow to help keep warm

• Decreases blood flow to help keep cool

Maintaining homeostasis

• Countercurrent exchange- exchange of heat via fluids or between fluids that are moving in the opposite direction

Maintaining homeostasis behavioral

• Maximize sunlight absorption • Postures• Huddling together• Torpor • Hibernation

Form and Function

Homeostasis

Feedback

Disruptions In Homeostasis

• Homeostatic disruptions are anything that affects the individual or the environment in which the individual lives in

• Can be: • Molecular level• Ecosystem level

Diabetes

• Problem in feedback loops

• Can be • Type I (juvenile or child onset)• Type II

• Both cases cells are not communicating in the feedback loop dealing with blood sugar

Alteration of feedback

Insulin

Blood glucose

glucagon

Diabetes

Molecular disruption

Dehydration:

Molecular disruption

1-2% loss increase in body temperature, thirst, discomfort, loss of appetite, dry skin, constipation

5% loss All above and: headaches, increased heart rate, nausea, tingling limbs

6% loss All of the above and: muscle spasms, cramping

10% loss All above and: susceptibility to heat stroke, circulatory collapse, vision dims, urination stops

50% loss death

Ecosystem disruptions

• Invasive species: A species, often introduced by humans, that takes hold outside its native range

Form and Function

Homeostasis

Feedback

Form and Function

• Response: Anything an organism does as a result of its surroundings

• Can be: • Behavioral • Physiological

Behavioral Responses

• Occurs as a population or a group of organisms• Examples:

1. Hibernation

2. Migration

Can be learned or inherited

Physiological responses

• Changes within the organism• Examples:

1. Shivering

2. Sweating- evaporative cooling

Form and Function

Homeostasis

Feedback

Physiological-Defense

• Plants and animals defend themselves from pathogens• Pathogens- invaders • 2 major forms of defense:

1. Nonspecific

2. Specific

Nonspecific

• Kills anything that invades (skin, saliva, normal bacteria, swelling, inflammation etc.)

• Plants sense pathogens using Hypersensitive Responses

Nonspecific - hypersensitive

• R gene in chromosomes – senses invading proteins

• R gene will initiate a hypersensitive response

• Oxidative burst – apoptosis • Proteins sent to adjacent cells

will change cell wall

• Memory does not occur

Specific

• Specific responses identify pathogens and attack them• Occurs in 2 forms:

1. Humoral – occurs in humor/liquid/blood/lymphatic

2. Cell mediated – target infected cells

Humoral

• Humoral responses are governed by B cells• B cells produce memory Antibodies• Antibodies target invaders• Invaders are called antigens -

Humoral

• Antibodies have antigen-binding sites

• Antigen- is an antibody generating organism

• fungus, bacteria, virus etc.

Humoral

1. Antigen present – invader

2. Antigen is engulfed (eaten) by a WBC or macrophage

3. WBC will take some of the antigen and put it on the surface of its cell (Antigen Presenting Cell)

4. Helper T cells- recognize the shape of the antigen

5. Helper T cells- activate B cells to make antibodies

a. plasma B – makes antibodies

b. memory B

6. B cells invade antigens

Cell-mediated

• This response targets infected cells• Called cytotoxic T cells – kills own cells that are infected

Form and Function

Homeostasis

Feedback

Physiological- Development

How does this happen?

Physiological

• Seed Germination – • When planting seeds it needs 2 things to survive (water and

temperature) must be in correct combination• Germinating cells will appear different

Physiological

• First step in development is cellular differentiation

• DNA will express specific proteins that determine each tissue – called tissue specific proteins

• Cells will eventually specialize

Physiological - differentiation

• Zygote makes a copies of itself• Forms a sphere (blastula) • Blastula folds in on itself (gastrula) forms ectoderm,

mesoderm and endoderm• Transcription factors give off proteins that help to

determine what should happen

Physiological - induction

• Step 2 is embryonic induction:• Cells induce other cells to become like them, give off

proteins • Cells induce adjacent cells next to it

Physiological – cell death

• Just as important as cell growth• Hid, Grim, Reaper Genes• These genes are needed between fingers and toes etc. • microRNA genes – control hid, grim, reaper genes

Physiological- Homeotic genes

• How do cells “know” the body plan of organisms?• Homeotic genes – are a series of genes that “tell”

drosophila where to put the organs/appendages etc.• Famous ones are HOX genes

We learned from the mutants

Ultrabithroax will duplicate the thorax

Antp- one leg will grow of the head

Series of genes that codes for body plan

Form and Function

Homeostasis

Feedback

Timing and control

When traveling – especially across time zones jet-lag occurs

Timing and control - plants

1. Phototrophism – how plants grow toward or away from light

Toward light +

Away from light –

Hormone: Auxin

Timing and control - plants

2. Photoperiodism – how plants respond to changing amounts of light during the season

Phytochrome – light receptor- when absorb light, will change shape to let plant know what time of day and season it is (regulates cellular activities)

Timing and control - animals

• Circadian rhythms – • Animals sense light- • Sent to pineal gland • Releases melatonin which sets internal clock

Timing and control – bacteria

• Bacteria use Quorum Sensing• How bacteria talk or communicate with each other• Can be among species or between species• Bacteria give off autoinducers

Form and Function

Homeostasis

Feedback

Where does evolution fit?

How does change support homeostasis???

Homeostatic evolution

• Homeostasis reflects BOTH common ancestry and divergence!!!

• Continuity • Change

Continuity - Example

• Excretory system – All serve same purpose (get rid of waste)• Flatworms• Earthworms• Vertebrates

flatworms

• Excretory system called Protonephridia• Protonephridia forms networks of tubes connected to

external openings• Flame bulbs (cells) is how waste moves out of the

platyhelminthes

• Rotifers, some annelids, mollusc larvae, and lancelets

Annelids

• Earthworms contain segments have Metanephridia• Metanephridia are excretory organs that collect fluid

directly from the coelom• Each segment has one• Cilia funnel surrounds the opening which excretes waste

out of earthworm

Vertebrates

• Kidneys are present, function in osmoregulation and excretion

• Kidney tubules – nephron

Continuity –

Each phylum of organisms has a way to get rid of waste.

Each are similar but with modification “descent with modification”

Common ancestry

Change

• Homeostatic mechanisms also support change in response to changing environments

• Vertebrates must have oxygen in their environment, must have water in their environments

change

• Example – Respiratory systems

• Aquatic • Terrestrial

Form and Function

Homeostasis

Feedback

Where does evolution fit?

How does change support homeostasis???

Homeostasis contd.

• Organisms exhibit complex properties between organs and systems

• Example: Respiratory and Circulatory systems

Homeostasis

Homeostasis

Homeostasis

Homeostasis

Nervous System works with all systems

How does nervous system function??

Relay system

1. Stimulus2. Receptor3. Afferent pathway 4. Integration center5. Efferent pathway6. Effector organ7. Response

Divisions of nervous System

N.S

Peripheral

Somatic Autonomic

Parasympathetic Sympathetic

Central

Nerve impulses

Nerve impulses

Nerve impulses

Steps:

1. Resting (polarized)

K+

K+K+

Na+

Na+

Na+ Na+

Na+

Na+

Na+

Na+

Na+

Nerve impulses

• Step 2 Depolarization (polarity is reversed)

Nerve impulses

• Step 3 Repolarization • initiation of sodium potassium pumps • Restores initial electrical configuration

Form and Function

Homeostasis

Feedback

Environment

Disruption

Abiotic Biotic

Responses

General

Behavioral • Timing and

coordination of events

Physiological • Defense • Development

Behaviors

• Fixed action pattern

Ex: sticklebacks

Behaviors

• Migration – using environmental cues to guide regular, long-distance change in location

Behaviors

• Courtship – fixed behaviors

1. Visual communication2. Chemical communication 3. Tactile communication

Behaviors

• Cortship

Behaviors

• Honey bee Dances

Behaviors

Behaviors

Behaviors

• Innate behavior – developmentally fixed within an organism

• Learning- the modification of behavior based on specific experiences

Behaviors

• Imprinting – formation at a specific stage in life a long-lasting behavioral response to a particular individual or object

Behaviors

• Associative learning – associate environmental features with another

Classical Conditioning – Pavlov’s dogOperant conditioning – trial and error

Behaviors

• Social Learning:

Behaviors

• Foraging – food-obtaining behaviors

Behaviors

Behaviors

• Mating Systems and Mate Choice• Promiscuous mating

– no strong pair bond

• Monogamous – mates remain together for a longer period

• Polygamous – one male and several females or visa versa

Behaviors

• Altruism – selflessness, reduces an animal’s individual fitness, but increases the fitness of the others in the population