Cell community multicelled organism population the biosphere ecosystem Levels of Living Organization

cell

community

multicelledorganism

population

the biosphere

ecosystem

Levels of Living Organization

Kingdoms

• Animalia

• Fungi

• Monera-archaebacteria and eubacteria

• Plantae

• Protista-amebas and algae

Carbohydrates

• Monosaccharides– Simple sugars – Glucose, fructose, ribose

• Oligosaccharides– Short-chain carbohydrates – Sucrose

• Polysaccharides– Complex carbohydrates – Glycogen, starch, cellulose, chitin

Sucrose Formation

Glucose(monosaccharide)

Sucrose (disaccharide)

+ H2O

Fructose(monosaccharide)

Major Polysaccharides

cellulose

amylose (a starch)

glycogen

• Tend to be insoluble in water• Fats• Phospholipids have fatty acid tails• Waxes• Sterols: have a fused carbon ring

Lipids

Fatty Acids

• Carboxyl group at one end

• Carbon backbone

• Saturated or unsaturated

linolenic acid

stearic acid

saturated unsaturated

Proteins

• Of all biological molecules, proteins are the most diverse

• Proteins are essentially amino acids joined by peptide bonds

• Three or more joined amino acids make a polypeptide chain

Protein Synthesis

• Peptide bond

– Condensation reaction links amino group of

one amino acid with carboxyl group of next

Water forms as a by-product

newly forming polypeptide chain

Another peptide bond forms. Water forms as a by-product.

Peptide bond forms.Water forms as a by-product.

Another peptide bond forms.Water forms as a by-product.

Another peptide bond forms.Water forms as a by-product.

Nucleotides

• Energy carriers

• Coenzymes

• Chemical messengers

• Building blocks for nucleic

acids

• Sugar

• At least one

phosphate group

• Nitrogen-

containing base

Nucleotide Structure

ATPbase

sugar

3 phosphate groups

DNA

• Double-stranded • Sugar-phosphate

backbone• Covalent bonds in

backbone• H bonds between

bases

nucleotides

DNA

• Double-stranded • Sugar-phosphate

backbone• Covalent bonds in

backbone• H bonds between

bases

hydrogen bonds

Cell Theory

• Every organism is composed of one

or more cells

• Cell is smallest unit having properties of life

• Continuity of life arises from growth and division

of single cells

Structure of Cells

All start out life with:– Plasma membrane

– Region where DNA is stored

– Cytoplasm

Two types:– Prokaryotic

– Eukaryotic

Most Cells Are Really Small

• Surface-to-volume ratio

• The bigger a cell is, the less surface area

there is per unit volume

• Above a certain size, material cannot be

moved in or out of cell fast enough

0.5 1.0 1.5

0.79

0.06

3.14 7.07

0.52 1.77

Diameter (cm):

Surface area (cm2):

Volume (cm3):

Surface- to-volume ratio:

13.17:1 6.04:1 3.99:1

9x’s

30x’s

Structure of Cell Membranes

• Fluid mosaic model

• Mixed composition:– Phospholipid bilayer – Glycolipids– Sterols– Proteins

one layerof lipids

one layerof lipids

one layerof lipids

one layerof lipids

Phosphate head

2 fatty acid tails

head

tails

H2O

active transporters

passivetransporter

receptor protein

recognition protein

cell wall chloroplast central vacuole

nuclear envelopenucleolusDNA in nucleoplasm

Nucleus:

rough ER

smooth ER

Golgi body

lysosome-like vesicle

plasma membrane

plasmodesma

mitochondrion

Cytoskeleton:

microtubules microfilaments

Plant Cell

nuclear envelope

nucleolusDNA in nucleoplasm

Nucleus:

rough ER

smooth ER

Golgi bodylysosome

plasma membrane

centrioles

mitochondrion

Cytoskeleton:

microtubules microfilaments

intermediatefilaments

Animal Cell

Enzymes

• Catalyze (speed up) metabolic reactions

• Recognize and bind specific substrates

• Act repeatedly

• Most are proteins

Activation Energy

• For a reaction to occur, an energy barrier must be surmounted

• Enzymes make the energy barrier smaller

activation energywithout enzyme

activation energywith enzyme

energyreleased

by thereaction

products

starting substance

glucose transporter

solute (glucose)

high

low

Passive Transport

ATP

ADP

Pi

higher calcium concentration

lower calcium concentration

Calcium pump

Active Transport

Pigments

• Color you see is the wavelengths not absorbed

• Light-catching part of molecule often has alternating single and double bonds

• Light energy destabilizes bonds and boosts electrons to higher energy levels

Chlorophylls reflect green wavelengths

Chloroplast

two outer membranes

inner membrane system(thylakoids connectedby channels)

stroma

Organelle of photosynthesis in plants and algae

sunlightenergy

H2O(water)

ATP

NADPH

O2 H2O (metabolic water)

light-dependentreactions

light-independent

reactions

glucose

NADP+

ADP + Pi

CO2

(carbon dioxide)

Light-Dependent Reactions

sunlight ATP

NADPH

ATP+Pi

H+O

H+

H+H+

H+ H+

H+

H+

NADP+

H2O e- e-

e-

photosystem II photosystem I

ATPsynthase

thylakoidmembrane

stroma

Calvin-Benson Cycle

ATP

NADPHATP

glucose1

Calvin-Bensoncycle

6 RuBP12 PGA

12 PGAL

6CO2

Roles of Mitosis

• Multicelled organisms

– Growth

– Cell replacement

• Some protistans, fungi, plants, animals

– Asexual reproduction

Mitosis

• Period of nuclear division

• Usually followed by cytoplasmic division

• Four stages:

Prophase

Metaphase

Anaphase

Telophase

Transition to Metaphase

• Spindle forms

• Spindle microtubules become attached to the two sister chromatids of each chromosome

Metaphase

• All chromosomes are lined up at the spindle equator

• Chromosomes are maximally condensed

Anaphase

• Sister chromatids of each chromosome are pulled apart

• Once separated, each chromatid is a chromosome

Telophase

• Chromosomes decondense

• Two nuclear membranes form, one around each set of unduplicated chromosomes

Results of Mitosis

• Two daughter nuclei • Each with same

chromosome number as parent cell

• Chromosomes are in unduplicated form

Sexual Reproduction

• Involves

– Meiosis

– Gamete production

– Fertilization

• Produces genetic variation among offspring

Sexual Reproduction Shuffles Alleles

• Through sexual reproduction, offspring inherit new combinations of alleles, which lead to variations in traits

• This variation in traits is the basis for evolutionary change

Chromosome Number

• Sum total of chromosomes in a cell

• Germ cells are diploid (2n)

• Gametes are haploid (n)

• Meiosis halves chromosome number

Crossing Over

• Each chromosome becomes zippered to its homologue

• All four chromatids are closely aligned

• Nonsister chromosomes exchange segments

Effect of Crossing Over

• After crossing over, each chromosome

contains both maternal and paternal

segments

• Creates new allele combinations in

offspring

Allele Combinations

• Homozygous – having two identical alleles at a locus– AA or aa

• Heterozygous – having two different alleles at a locus– Aa

Homologous chromosomes

Pair of alleles at a gene locusA a

Monohybrid Cross

Illustrated

True-breedinghomozygous recessiveparent plant

True-breedinghomozygous dominantparent plant

An F1 plantself-fertilizesand producesgametes:

F1 PHENOTYPES

F2 PHENOTYPES

aa

Aa

AA

aaAa

Aa

Aa Aa

Aa Aa

Aa Aa

Aa Aa

Aa

Aa

AA

aa

A

A

A

A

a a

a

a

AA

Monohybrid Cross

Illustrated

True-breedinghomozygous recessiveparent plant

True-breedinghomozygous dominantparent plant

An F1 plantself-fertilizesand producesgametes:

F1 PHENOTYPES

F2 PHENOTYPES

aa

Aa

AA

aaAa

Aa

Aa Aa

Aa Aa

Aa Aa

Aa Aa

Aa

Aa

AA

aa

A

A

A

A

a a

a

a

AA

F1: first generationPhenotype: observable traitsGenotype: particular alleles

Monohybrid Cross

Illustrated

True-breedinghomozygous recessiveparent plant

True-breedinghomozygous dominantparent plant

An F1 plantself-fertilizesand producesgametes:

F1 PHENOTYPES

F2 PHENOTYPES

aa

Aa

AA

aaAa

Aa

Aa Aa

Aa Aa

Aa Aa

Aa Aa

Aa

Aa

AA

aa

A

A

A

A

a a

a

a

AA

Monohybrid Cross

Illustrated

True-breedinghomozygous recessiveparent plant

True-breedinghomozygous dominantparent plant

An F1 plantself-fertilizesand producesgametes:

F1 PHENOTYPES

F2 PHENOTYPES

aa

Aa

AA

aaAa

Aa

Aa Aa

Aa Aa

Aa Aa

Aa Aa

Aa

Aa

AA

aa

A

A

A

A

a a

a

a

AA

Average F2 dominant-to-recessive ratio: 3:1

Dihybrid Cross

Aa X BbExperimental cross between individuals that are heterozygous for different versions of two traits

Dihybrid Cross: F1 Results

AABB aabbx

AaBb

AB AB ab ab

TRUE-BREEDING PARENTS:

GAMETES:

F1 HYBRID OFFSPRING:

purple flowers, tall

white flowers,dwarf

all purple-flowered, tall

A a

Dihybrid Cross: F1 Results

AABB aabbx

AaBb

AB AB ab ab

TRUE-BREEDING PARENTS:

GAMETES:

F1 HYBRID OFFSPRING:

purple flowers, tall

white flowers,dwarf

all purple-flowered, tall

B b

AB

AaBb AaBb

AaBb AaBb

AB

ab

ab

Are all the plants tall or dwarf?

Purple flowers, tall plant

White flwrs,Dwarf plant

1/16aaBB

1/16aaBb

1/16aaBb

1/16Aabb

1/16Aabb

1/16AAbb

1/16AABB

1/16AABb

1/16AaBB

1/16AaBb

1/16AABb

1/16AaBb

1/16AaBB

1/16AaBb

1/16AaBb

1/4 AB 1/4 Ab 1/4 aB 1/4 ab

1/16aabb

1/4 AB

1/4 Ab

1/4 aB

1/4 ab

AaBb AaBbX

1/16 white-flowered, dwarf

3/16 white-flowered, tall

3/16 purple-flowered, dwarf

9/16 purple-flowered, tall

Dihybrid Cross: F2 Results

1/16aaBB

1/16aaBb

1/16aaBb

1/16Aabb

1/16Aabb

1/16AAbb

1/16AABB

1/16AABb

1/16AaBB

1/16AaBb

1/16AABb

1/16AaBb

1/16AaBB

1/16AaBb

1/16AaBb

1/4 AB 1/4 Ab 1/4 aB 1/4 ab

1/16aabb

1/4 AB

1/4 Ab

1/4 aB

1/4 ab

AaBb AaBbX

1/16 white-flowered, dwarf

3/16 white-flowered, tall

3/16 purple-flowered, dwarf

9/16 purple-flowered, tall

Dihybrid Cross: F2 Results

12 purple / 4 white: 3:1

12 tall / 4 dwarf: 3:1

Structure of DNA

2nm diameter overall

0.34 nm between each pair of bases

3.4 nm length of each full twist of helix

In 1953, Watson and Crick showed that DNA is a double helix

Composition of DNA

• Amount of adenine relative to guanine differs

among species

• Amount of adenine always equals amount of thymine, and amount of guanine always equals amount of cytosine

A=T and G=C

GGGCCATG

CCCGGTAC

Human Genome

A specific gene sequence for a bird, lizzard,insect or human

Unity and Diversity of Life

DNA Structure Helps Explain How It Duplicates

• DNA is two nucleotide strands held

together by hydrogen bonds

• Hydrogen bonds between two strands

are easily broken

• Each single strand then serves as

template for new strand

DNA Replication

newnew old old

• Each parent strand

remains intact

• Every DNA

molecule is half

“old” and half “new”

Base Pairing during Replication

• Each old strand serves as the template for complementary new strand

• Semiconservative replication

• Why is this method used?

Enzymes in Replication

• Enzymes unwind the two strands and their

complementary base pairs unzip

• DNA polymerase attaches new

complementary nucleotides

• DNA ligase fills in gaps

• Enzymes wind two strands together

Natural Selection

• Natural selection among individuals of a population is an outcome of variation in traits that affect which individuals survive and reproduce in each generation

• This process results in adaptation to the environment (increases fitness)

Adaptation

• Some heritable aspect of form, function, or behavior that improves the odds for surviving and reproducing

• Environment specific

• Outcome of natural selection

Example: Morpho Butterfly

Results of Natural Selection

Three possible outcomes:

• A shift in the range of values for a given trait in some direction

• Stabilization of an existing range of values

• Disruption of an existing range of values

Directional Selection

Allele frequencies shift in consistent direction over time

Range of values at time 3

Num

ber

of

indi

vidu

als

Range of values at time 2

Num

ber

of

indi

vidu

als

Range of values at time 1

Num

ber

of

indi

vidu

als

Why are insects so adept at developing resistance?

Stabilizing Selection

Intermediate forms are favored and extremes are eliminated

Range of values at time 1

Num

ber

of

indi

vidu

als

Range of values at time 2

Num

ber

of

indi

vidu

als

Range of values at time 3

Num

ber

of

indi

vidu

als

Disruptive Selection

• Happens when forms at both ends of the range of variation are favored

• Intermediate forms are selected against

Range of values at time 1

Num

ber

of

indi

vidu

als

Range of values at time 3

Num

ber

of

indi

vidu

als

Range of values at time 2

Num

ber

of

indi

vidu

als

Sexual Selection

• Selection favors certain secondary sexual characteristics

• Through nonrandom mating, alleles for preferred traits increase

• Leads to increased sexual dimorphism

Sexual Dimorphism and Trait Preference

Genetic Drift

• Random change in allele frequencies brought about by chance

• Effect is most pronounced in small populations

• Sampling error: fewer times an event occurs, greater the variance in outcome

Computer Simulation:Small Population

AA in five populations

allele A lostfrom fourpopulations

1.0

0.5

01 505 10 15 20 25 30 35 40 45

Generation (25 stoneflies at the start of each)

Frequency of A

Computer Simulation:Large Population

allele A neitherlost norfixed

1.0

0.5

01 505 10 15 20 25 30 35 40 45

Generation (500 stoneflies at the start of each)

Founder Effect

• Effect of drift when a small number of individuals starts a new population

• By chance, allele frequencies of founders may not be same as those in original population

• Effect is pronounced on isolated islands

phenotypes of original population

phenotype of island population

Gene Flow

• Physical flow of alleles into a population

• Tends to keep the gene pools of populations similar

• Counters the differences that arise from mutation, natural selection, and genetic drift

+

Gene Flow?

Biogeography

• Two ways animals and plants can be distributed:– Slow geologic change– Accidental or unlikely colonization

– Leads to Speciation: the creation of new species

Same latitudes

Biological Species Concept

“Species are groups of interbreeding natural populations that are reproductively isolated from other such groups.”

Ernst Mayr

Mechanisms of Speciation

• Allopatric speciation: Some sort of barrier arises and

prevents gene flow

• Sympatric speciation: species form w/out a barrier

(cichlids)

• Parapatric speciation: populations sharing a common

border; face different selection pressures along a habitat

gradient

Genetic Divergence

• Gradual accumulation of differences in the gene pools of populations

• Natural selection, genetic drift, and mutation can contribute to divergence

• Gene flow counters divergence

Genetic Divergence

time A time B time C time D

daughter species

parent species

If gene flow is prevented…

Speed of Speciation

• Gradual model: species originate by small morphological changes over long time spans

• Punctuated equilibrium: most morphological changes occur in only a brief period of time (often after mass extinctions)

Characteristics of Animals

• Multicelled heterotrophic eukaryotes

• Require oxygen for aerobic respiration

• Reproduce sexually, and perhaps asexually

• Motile at some stage

• Undergo development

Mammal Characteristics

• Hair

• Mammary glands

• Distinctive teeth

• Highly developed brain

• Extended care for the young

Three Mammalian Lineages

• Egg-laying mammals

• Marsupials (pouched mammals)

• Placental mammals

Monocots and Dicots

• Two major plant groups

• Same tissues, but arranged in different ways

• Dicots are the more diverse group

Dicot Monocot

cotyledons

Seeds

Dicot Monocot

Multiples of 3 Multiples of 4 or 5

Dicot Monocot

MonocotDicot

3 pores or furrows 1 pore or furrow

Monocot DicotVascular bundles in a ring in stem ground tissue

Vascular bundles throughout stem ground tissue

Flower Structure

• Nonfertile parts– Sepals – Receptacle – Petals

• Fertile parts– Male stamens – Female carpel

(ovary)

filament anther stigma style ovary

receptacle

sepal (all sepals combined are the flower’s calyx)

OVULE (forms within ovary)

petal (all petals combined are the flower’s corolla)

STAMEN(male reproductive part)

CARPEL(female reproductive part)

Pollen Formation

pollen sacanther

filament

microspore mother cell

Meiosis

pollen tubesperm nucleimature male gametophyte

stigma

style of carpel

Diploid StageHaploid Stage

microspores

pollen grain

• Each anther has four pollen sacs

• Inside pollen sacs, cells undergo meiosis and cytoplasmic division to form microspores • Microspores undergo

mitosis to form pollen grains

seedling (2n)

meiosis

ovary (cutaway view)

ovary wall

stalk

an ovule

cell

embryo sac inside

ovule

pollen tube

endospermmother cell(n + n)

egg (n)

Diploid StageHaploid Stage

seed

double fertilization

mature female gametophyte

Events inside Ovule integument

embryoendosperm

seed coat

Seed Germination

• Process by which the plant embryo resumes growth after seed dispersal

• Depends upon environmental factors– Temperature – Soil moisture (hydrophilic proteins)– Oxygen levels (aerobic respiration)

Biological Clocks

• Internal timing mechanisms

– Trigger shifts in daily activity

– Help induce seasonal adjustments

• Phytochrome is part of the switching

mechanism

– Blue-green plant pigment

Acute Inflammation

• Nonspecific response to foreign invasion, tissue damage, or both

• Destroys invaders, removes debris, and prepares area for healing

• Characterized by redness, swelling, warmth, and pain

Inflammation

• Mast cells release histamine, which causes…

• Capillaries dilate and leak (vasodilation)

• Complement proteins attack bacteria

• White cells attack invaders and clean up

Features of Immune Responses

• Self/nonselfrecognition

• Specificity

• Diversity

• Memory

Memory and Effector Cells

• When a B or T cell is stimulated to divide, it produces more than one cell type

• Memory cells: set aside for future use

• Effector cells: engage and destroy the current threat

Allergies

• Immune reaction to a harmless substance• Genetic predisposition• Immunoglobulins (IgE) responds to antigen by

binding to mast cells and basophils• These cells secrete the substances that

cause symptoms

antigen-presenting cell

Antibody-mediatedimmune response

or B cell

antigen-presenting cell

Cell-mediatedimmune response

Structure of a Neuron

dendrites

cell body

TRIGGER ZONE

INPUT ZONE

CONDUCTING ZONE

OUPUT ZONEaxon

axon endings

Action Potential

• A brief reversal in membrane potential

• Voltage change causes voltage-gated channels in the membrane to open

• Inside of neuron briefly becomes more positive than outside

Action Potential

Na+

Na+Na+

Na+

Na+

Na+

K+

K+

K+

Na+Na+

K+ K+K+

K+

Na+

1 2

3 4

Electrical disturbanceElectrical disturbance

Central and Peripheral Nervous Systems

• Central nervous system (CNS)

– Brain

– Spinal cord

• Peripheral nervous system

– Nerves that thread through the body

Peripheral Nervous System

• Somatic nerves – Motor functions– Muscles, tendons, skin– (Shown in green)

• Autonomic nerves– Visceral functions– To/from organs– (Shown in red)

Two Types of Autonomic Nerves

Sympathetic

Parasympathetic

• Most organs receive input from both

• Usually have opposite effects on organ

Trophic Levels in Prairie

5th

4th

3rd

2nd

1st

Fourth-level consumers (heterotrophs):

Top carnivores, parasites, detritivores, decomposers

Third-level consumers (heterotrophs):

Carnivores, parasites, detritivores, decomposers

Second-level consumers (heterotrophs):

Carnivores, parasites, detritivores, decomposers

First-level consumers (heterotrophs):

Herbivores, parasites, detritivores, decomposers

Primary producers (autotrophs):

Photoautotrophs, chemoautotrophs

marsh hawk

garter snake

cutworm

plants

upland sandpiper

Tropical Rice: Three Pathways Support Natural Enemies

RICE PLANT

PESTS

DETRITIVORES

NATURAL ENEMIES

ORGANIC MATTER

FILTER FEEDERS

MICRO-ORGANISMCYCLERICE

PLANT

PESTS

DETRITIVORES

NATURAL ENEMIES

ORGANIC MATTER

FILTER FEEDERS

MICRO-ORGANISMCYCLE

Simple Ecosystem

Modelenergy input from sun

nutrientcycling

PHOTOAUTOTROPHS(plants, other producers)

HETEROTROPHS(consumers, decomposers)

energy output (mainly heat)

Bio

mas

s

Con

cent

ratio

n

Hormones and Behavior

• In voles, the hormone oxytocin plays a role in pair bonding

• When pair-bonded females are injected with a drug that blocks oxytocin they dump their partners

• Different vole species have different mating patterns that correlate with differences in number and distribution of oxytocin receptors in brain

Instinctive Behavior

• Performed without having been learned

• Usually triggered by simple sign stimuli

• Response is a stereotyped motor program, a fixed-action pattern

Learned Behavior

• Responses change with experience

• Imprinting– Time dependent form of learning– Triggered by exposure to a simple sign

stimulus– Geese hatchlings treat the first moving

object they see as their mother

Bird Song: Instinct + Learning

• Bird comes prewired to listen to certain acoustical cues; instinctively pays attention to particular sounds

• Which dialect the bird sings depends on what song it hears; it learns the details of the song from others around it

Communication Signals

• Intraspecific signals will evolve only if they benefit both signaler and receiver

• Variety of signal modalitiesPheromones Tactile signals

Visual signals Acoustical signals

Male Reproductive Strategy

• Produce energetically inexpensive sperm

• Often provide no parental care

• Often maximize reproductive success by mating with as many females as possible

Female Reproductive Strategy

• Produce large, energetically expensive eggs

• Often provide parental care

• Often increase reproductive success by increasing the quality of their mates

“Farmscaping” is a whole-farm, ecological approach to pest management. It can be defined as the use of any form of secondary or non-crop vegetation in an attempt to attract, deter, or otherwise influence insect populations.

Farmscaping

Farmscaping Principles

Several alternatives have been proposed to explain the reduced densities in some vegetationally diverse systems:

• Resource Concentration Hypothesis: specialist herbivores are more likely to find and remain in pure stands of plants, resulting in higher pest populations

• Enemies Hypothesis: predators and parasitoids cause greater mortality to herbivores in diverse vegetational stands

Farmscaping Principles cont’d

• Plant Apparency Hypothesis: Plants which are more “apparent” are more vulnerable to certain types of herbivory

Unapparent vs. Apparent Plants * polyculture vs. monculture* annual vs. perennial* large size vs. small size* small defense investment vs. large defense investment* specific defenses geared towards specialists

vs.broad range defenses for generalists

Insectary Habitats

• Composed of annual species of plants, and are designed to attract beneficial insects

• Supplements crops by generating resources required by beneficial insects

• Nutritional resources such as pollen, nectar, and honeydew are capable of increasing the effectiveness of natural enemies

• Not otherwise provided in a monocultural setting

Trap Crops

• Typically annuals, which are designed to attract pests away from primary crops

• Based on the notion that insects posses inherent preferences for specific types of vegetation

• Capable of dramatically reducing pest management treatments

• Thereby preserves the natural enemies present in the field

Hedgerows

• Hedgerows are established habitats located along field edges

• Mostly perennial plants, and are designed to establish populations of beneficial insects

• Produce “islands” that are free of disturbance year round

• These areas then generate micro-climates, micro-habitats, and overwintering sites, which all foster insect diversity

Discussion: Aphid Arrival Time

Field Experiment Cage Experiment

% H

arve

st

Early Mid

Seasonal Aphid Arrival TimeSeasonal Aphid Arrival Time