Diversity of Organisms
Structure and Function of Plants and Animals
Reproduction, growth, and development
Question #62: What patterns of reproduction and development are found in plants and animals and how
are they regulated?
•
Asexual Reproduction:
–
Budding -- part of individual undergoes repeated mitotic
divisions to produce a new individual that breaks off --
e.g. hydra, sea anemone.
–
Fragmentation part of parent falls off or is broken off
-- fragment undergoes repeated mitotic divisions to
produce an entire individual -- e.g. starfish, sponge.
•
Some species of animals have evolved from a
sexual mode of reproduction back to an asexual
mode:
–
Parthenogenesis -- development of new individuals from
ova that are not fertilized by male gametes
Sexual reproduction -- involves production of
haploid gametes and formation of zygotes
through fertilization
•
Fertilization may be external of internal to the
animal.
–
External fertilization-- usually seen in aquatic animals
such as fish -- -- probability of fertilization increased
by production of huge numbers of gametes.
–
Internal fertilization -- increases probability that egg
and sperm will meet and that fertilization will occur --
structural adaptations to facilitate passage of sperm
into female reproductive tract.
Development of a male
gametophyte
(in pollen grain)
(a)
Microsporangium
(pollen sac)
(b) Development of a female
gametophyte (embryo sac)
Microsporocyte
Microspores (4)
Each of 4
microspores
Generative cell
(will form 2
sperm)
(LM)
75 m 20 m
100
m
MEIOSIS
MITOSIS
Male
gametophyte
(in pollen grain)
Nucleus of tube cell
Ragweed
pollen
grain
(colorized
SEM)
Key to labels
Haploid (
n
)
Diploid (2
n
)
(LM)
Embryo sac
Ovule
Megasporangium
Megasporocyte
Integuments
Micropyle
Surviving
megaspore
Antipodal cells (3)
Polar nuclei (2)
Egg (1)
Synergids (2)
Ovule
Integuments
F
em
al
e
g
am
et
o
p
h
y
te
(em
b
ry
o
sa
c)
Figure 38.3
Double Fertilization
Stigma
Pollen
tube
2
3
1
2 sperm
Style
Ovary
Ovule
Micropyle
Pollen
grain
Polar
nuclei
Egg
Ovule
Polar
nuclei
Egg
Synergid
2 sperm
Endosperm
nucleus (3n)
(2 polar nuclei
plus sperm)
Zygote
(2n)
•
21.1: Embryonic development involves cell division,
cell differentiation, and morphogenesis,
•
Embryonic development of multi-cellular organisms
–
A single-celled zygote
cells
tissues
organs
organ systems
organisms
Figure 21.3a, b
(a) Fertilized eggs
of a frog
•
The three processes of development overlap in time
Figure 21.4a, b
Animal development. Mostanimals go through some variation of the blastula and gastrula stages. The blastula is a sphere of cells surrounding a fluid-filled cavity. The gastrula forms when a region of the blastula folds inward, creating a tube—a rudimentary gut. Once the animal is mature, differentiation occurs in only a limited way—for the replacement of damaged or lost cells.
Plant development. In plants with seeds, a complete embryo develops within the seed. Morphogenesis, which involves cell division and cell wall expansion rather than cell or tissue movement, occurs throughout the plant’s lifetime. Apical meristems (purple) continuously arise and develop into the various plant organs as the plant grows to an indeterminate size.
Zygote (fertilized egg)
Eight cells Blastula (cross section)
Gastrula (cross section)
Adult animal (sea star) Cell
movement Gut
Cell division
Morphogenesis
Observable cell differentiation
Seed leaves
Shoot apical meristem
Root apical meristem
Plant Embryo inside seed Two cells
Zygote (fertilized egg) (a)
(b)
•
A summary of gene activity during
Drosophila
development
Hierarchy of Gene Activity in Early Drosophila Development
Maternal effect genes (egg-polarity genes)
Gap genes
Pair-rule genes
Segment polarity genes
Homeotic genes of the embryo
Other genes of the embryo
Segmentation genes
of the embryo
Widespread Conservation of
Developmental Genes Among Animals
•
Homeotic Genes are also called
Hox genes in animals
•
All homeotic genes contain a 180
NT homeobox region, coding for
a 60 AA homeodomain protein
–
Protein that acts as a selective transcription
factor
Figure 21.23
Adult fruit flyFruit fly embryo (10 hours)
Fly chromosome
Mouse chromosomes
Mouse embryo (12 days)
Adult mouse
Mechanisms of Plant Development
•
Cell lineage is much less important for pattern formation in
plants than in animals because most cells are totipotent
(reduced role of cytoplasmic determinants)
•
Development regulated by cell signaling and transcriptional
regulation
–
Signals can come from environment (sunlight, temp., gravity, etc.) and from cell
position
•
The embryonic development of most plants occurs inside
the seed making it harder to study
•
Morphogenesis and Differentiation can be studied at the
apical meristems
ALTERNATION OF GENERATION
•
GAMETOPHYTE GENERATION
–
All cells haploid (1N)
–
Grow from haploid spores
•
SPOROPHYTE GENERATION
–
Most cell diploid (2N)
–
Grow from diploid zygote
–
Produce haploid spores
•
Facilitates dispersal (happens
twice, with spores and gametes)
Question #63: What is the adaptive significance of alternation of generations in the
major groups of plants?
BRYOPHYTES: Nonvascular Plants
(not monophyletic)
•
Dominant Gametophyte
Mature sporophytes
Young sporophyte
Male gametophyte
Raindrop Sperm
Key
Haploid (n) Diploid (2n) Antheridia
Female gametophyte
Egg Archegonia
FERTILIZATION
(within archegonium) Zygote
Archegonium Embryo
Female gametophytes
Gametophore
Foot Capsule (sporangium) Seta Peristome
Spores Protonemata
“Bud”
“Bud”
MEIOSIS
Sporangium
Calyptra
Capsule with peristome (LM)
Rhizoid
Mature sporophytes Spores develop into threadlike protonemata.
1
The haploid protonemata produce “buds” that grow into gametophytes.
2
Most mosses have separate male and female gametophytes, with antheridia and archegonia, respectively.
3
A sperm swims through a film of moisture to an archegonium and fertilizes the egg.
4
Meiosis occurs and haploid spores develop in the sporangium of the sporophyte. When the sporangium lid pops off, the peristome “teeth” regulate gradual release of the spores.
8
The sporophyte grows a long stalk, or seta, that emerges from the archegonium.
6
The diploid zygote develops into a sporophyte embryo within the archegonium.
5
Attached by its foot, the sporophyte remains nutritionally dependent on the gametophyte.
SEEDLESS VASCULAR PLANTS
•
SPORE
bisexual gametophyte
–
Flagellated sperm generated by Antheridium swim
Evolution of Seed Plants
•
Reduced Gametophyte stage:
–
protected and nourished inside
sporophyte tissue
–
Heterosporous: separate male and
female gametophytes
•
Seed replaces spore for mechanism of
disperal
•
Megaspore develops within ovule
•
Microspore develop into pollen grain,
replacing flagellated sperm
Sporophyte dependent on gametophyte (mosses and other bryophytes).
(a) Large sporophyte and small, independent gametophyte (ferns and other seedless vascular plants).
(b)
Microscopic female gametophytes (n) in ovulate cones (dependent)
Sporophyte (2n), the flowering plant (independent) Microscopic male gametophytes (n) inside these parts of flowers (dependent)
Microscopic male gametophytes (n) in pollen cones
(dependent) Sporophyte (2n) (independent)
Microscopic female gametophytes (n) inside these parts of flowers (dependent)
Reduced gametophyte dependent on sporophyte (seed plants: gymnosperms and angiosperms). (c)
Gametophyte (n)
Gametophyte (n) Sporophyte (2n) Sporophyte
(2n)
Gymnosperm Life Cycle
•
Demonstrates key adaptations: dominance of sporophyte generation;
the advent of the resistant, dispersible seed; evolution of pollen that
brings gametes together.
Angiosperm Life Cycle
Structural, physiological, and behavioral adaptations
Question #64:
How does the organization of cells, tissues, and
organs determine structure and function in plant and animal
systems?
Contact with the environment
Diffusion
(a) Single cell
Mouth
Gastrovascular
cavity
Diffusion
Diffusion
(b) Two cell layers
•Cells require contact with aqueous medium
•Surface to Volume Ratio important, especially for simple
organisms lacking circulatory systems
•In Complex Organisms: common theme is extensive folding and
branched internal surfaces
Length = 5 Surface Area = 150 Volume = 125 Surface/Volume Ratio = 1.2
Internal exchange surfaces of complex animals
External environment
Food CO2 O2
Mouth
Animal body
Respiratory system
Circulatory system
Nutrients
Excretory system Digestive
system
Heart
Cells
Interstitial fluid
Anus Unabsorbed matter (feces)
Metabolic waste products (urine) The lining of the small intestine, a diges-
tive organ, is elaborated with fingerlike projections that expand the surface area for nutrient absorption (cross-section, SEM).
A microscopic view of the lung reveals that it is much more spongelike than balloonlike. This construction provides an expansive wet surface for gas exchange with the environment (SEM).
Inside a kidney is a mass of microscopic tubules that exhange chemicals with blood flowing through a web of tiny vessels called capillaries (SEM). 0.5 cm
10 µm
5
0
µ
m
Cells
organized into Tissues
organized into Organs
organized into Organ Systems
Structure and Function in Animal Tissues
EPITHELIAL TISSUE
Columnar epithelia, which have cells with relatively large cytoplasmic volumes, are often located where secretion or active absorption of substances is an important function.
A stratified columnar epithelium
A simple columnar
epithelium A pseudostratified ciliated columnar epithelium
Stratified squamous epithelia Simple squamous epithelia
Cuboidal epithelia
Basement membrane
40 µm
Epithelial tissue covers the
outside of the body and
lines organs and cavities
within the body with tightly
packed cells
Glandular Epithelial:
absorb or secrete
Organized by shape and
Pattern:
Simple: one layer
Stratified: multiple layers
Cuboidal: cube-shaped
(secretion)
Columnar: column
(secretion/absorption)
Squamous: floor tiles
(diffusion, or protection)
Connective tissue functions mainly to bind and support other tissues
Collagenous fiber Elastic fiber
Chondrocytes Chondroitin sulfate
Loose connective tissue
Fibrous connective tissue
100
µm
100 µm
Nuclei
30 µm
Bone Blood
Central canal
Osteon
700 µm 55 µm
Red blood cells White blood cell Plasma
Cartilage
Adipose tissue
Fat droplets
1
5
0
µ
m
CONNECTIVE TISSUE
•
The major types of
connective tissues in
vertebrates:
•
Loose connective tissue:
packing material
•
Adipose tissue: cushioning,
energy storage
•
Fibrous connective tissue:
Tendons (join muscles to
bones) and Ligaments (hold
bones together)
•
Cartilage: flexible support
•
Bone: mineralized, hard
support
•
Blood: transport and defense
Each has a structure
correlated with its specialized
function
Organs and Organ Systems:
Many organs have multiple tissue layers, held in place my mesenteries
inside body cavities
Organs are organized into Organ Systems
Morphology of a Flowering Plant
Flower:
Reproductive Adaptation of Angiosperms
•
Sepals: leaves enclose flower
•
Petals: attract pollinators
•
Stamens: male reproductive structure
consisting of - anther and filament
•
Carpels: female reproductive structure
consisting of - stigma, style, and ovary
•
Incomplete flowers- (grasses) lack at
least one of 4 major parts
•
Unisexual flower- have only male or
female parts
Examples of Differentiated Plant Cells
PARENCHYMA CELLS
COLLENCHYMA CELLS
SCLERENCHYMA CELLS
SUGAR-CONDUCTING CELLS OF THE PHLOEM WATER-CONDUCTING CELLS OF THE XYLEM
Parenchyma cells 60 m 80 m
5 m
25 m
Cell wall
Sclereid cells in pear
Fiber cells
Cortical parenchyma cells
Collenchyma cells
Vessel Tracheids 100 m
Tracheids and vessels
Vessel element
Vessel elements with partially perforated end walls
Pits
Sieve-tube members: longitudinal view
Companion cell
Sieve-tube member Sieve plate Nucleus
Cytoplasm Companion cell
30 m 15 m
Tracheids
Photosynthesis
Flexible support
Rigid support
Tissue Organization of Leaves
Flexible support
Photosynthesis
Protective layer
Protective layer
Question #65: How are structure and function related in the various organ systems
and how do the organ systems of animals interact?
•
41.4: Each organ of the mammalian digestive
system has specialized food-processing functions
IIeum of small
intestine Duodenum of small intestine
Appendix Cecum Ascending portion of large intestine
Anus Small intestine Large intestine Rectum Liver
Gall- bladder Tongue
Oral cavity Pharynx
Esophagus
Stomach Pyloric sphincter
Cardiac orifice
Mouth Esophagus
Salivary glands
Stomach
Liver Pancreas Gall- bladder
Large intestines Small intestines
Rectum Anus Parotid gland
Sublingual gland Submandibular gland Salivary glands
A schematic diagram of the human digestive system
Pancreas
Absorption of Nutrients
•
The small intestine has a huge surface area due to
the presence of villi and microvilli that are exposed
to the intestinal lumen absorption.
Epithelial cells
Key
Nutrient absorption
Vein carrying blood to hepatic portal vessel
Villi
Large circular folds
Intestinal wall Villi
Epithelial cells
Lymph vessel Blood
capillaries
Lacteal Microvilli (brush border)
Muscle layers
FISHES AMPHIBIANS REPTILES (EXCEPT BIRDS) MAMMALS AND BIRDS
Systemic capillaries
Systemic capillaries
Systemic capillaries
Systemic capillaries
Lung capillaries
Lung capillaries
Lung and skin capillaries
Gill capillaries
Right Left Right Left Right Left
Systemic circuit Systemic
circuit Pulmocutaneous
circuit
Pulmonary
circuit Pulmonary circuit
Systemic circulation
Vein Atrium (A) Heart: ventricle (V) Artery Gill circulation
A
V V
V V V
A A A Left Systemic A A
aorta Right
systemic aorta
Figure 42.4
•
The effectiveness of gas exchange in some gills
Countercurrent exchange
Figure 42.21
Gill arch
Water flow Operculum
Gill arch
Blood vessel
Gill filaments
Oxygen-poor blood Oxygen-rich blood
Water flow over lamellae showing % O2
Blood flow through capillaries in lamellae showing % O2
Lamella
O2
Lungs
Branch from the pulmonary vein (oxygen-rich blood) Terminal bronchioleBranch from the pulmonary artery (oxygen-poor blood)
Alveoli
Colorized SEM SEM
5
0
µ
m
5
0
µ
m
Heart Left lung Nasal cavity Pharynx
Larynx
Diaphragm Bronchiole Bronchus Right lung Trachea Esophagus
How a Bird Breathes
INHALATION Air sacs fill
EXHALATION Air sacs empty; lungs fill Anterior
air sacs
Trachea
Lungs Lungs
Posterior air sacs
Air Air
1 mm Air tubes
(parabronchi) in lung
Figure 42.25
Figure 44.13c, d
Juxta- medullary nephron
Cortical nephron
Collecting duct
To renal pelvis
Renal cortex
Renal medulla
20 µm Afferent arteriole from renal artery Glomerulus
Bowman’s capsule Proximal tubule
Peritubular capillaries
SEM Efferent arteriole from glomerulus
Branch of renal vein Descending limb Ascending limb Loop
of Henle
Distal tubule
Collecting duct
(c) Nephron
Vasa recta
(d) Filtrate and blood flow
•
Concept 48.5: The vertebrate nervous system is regionally
specialized
•
In bilateral organisms, particularly vertebrates, the nervous
system shows a high degree of cephalization and distinct CNS
and PNS components
–
CNS: Brain and Spinal cord
–
PNS: Nerves and Ganglia
Figure 48.19
Central nervous
system (CNS) Peripheral nervous system (PNS)
Brain Spinal cord
Cranial nerves
Ganglia outside CNS Spinal nerves
The Peripheral Nervous System
•
The PNS transmits information to and from the CNS
–
Crucial in regulating a vertebrate’s movement and internal
environment
•
The PNS has two functional components
–
The somatic nervous system and the autonomic nervous system
Peripheral nervous system
Somatic nervous system
Autonomic nervous system
Sympathetic division
Parasympathetic division
Enteric division
Parasympathetic division Sympathetic division Action on target organs: Action on target organs: Location of
preganglionic neurons:
brainstem and sacral segments of spinal cord
Neurotransmitter released by preganglionic neurons:
acetylcholine
Location of postganglionic neurons:
in ganglia close to or within target organs
Neurotransmitter released by postganglionic neurons:
acetylcholine
Constricts pupil of eye
Stimulates salivary gland secretion
Constricts bronchi in lungs
Slows heart
Stimulates activity of stomach and
intestines
Stimulates activity of pancreas
Stimulates gallbladder
Promotes emptying of bladder
Promotes erection of genitalia
Cervical
Thoracic
Lumbar
Synapse Sympathetic ganglia
Dilates pupil of eye
Inhibits salivary gland secretion
Relaxes bronchi in lungs
Accelerates heart
Inhibits activity of stomach and intestines
Inhibits activity of pancreas
Stimulates glucose release from liver; inhibits gallbladder
Stimulates adrenal medulla
Inhibits emptying of bladder
Promotes ejaculation and vaginal contractions Sacral
Location of preganglionic neurons:
thoracic and lumbar segments of spinal cord
Neurotransmitter released by preganglionic neurons:
acetylcholine
Location of postganglionic neurons:
some in ganglia close to target organs; others in a chain of ganglia near spinal cord
Neurotransmitter released by postganglionic neurons:
norepinephrine
Figure 48.22