Post on 20-Dec-2015
transcript
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