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Characteristics of Life
A. Use Energy (the ability to do work) to grow
B. Metabolism – maintain complex chemical reactions
C. Homeostasis – maintain stable internal environment
D. Respond to stimuli – sense organsE. Reproduce – pass genes on to next
generation
Energy Utilization - Organisms take in energy and transform it to do many kinds of work. This fish obtains fuel from the sea urchin and uses energy stored in the molecules of its food to power swimming and other work.
Metabolism - This protein cascade is an example of the chemical reactions that take place in organisms. The product of one reaction becomes a catalyst for a second reaction.
Homeostasis – regulatory mechanisms maintain an organism’s internal environment within tolerable limits, even though the external environment may fluctuate. In this example, regulation of the amount of salt flowing through the seagull’s body fluids is controlled by glands on the bill that excrete excess ions.
Respond to stimuli – When threatened this squid will change colors in order to blend in with it’s surroundings
Reproduce – Organisms reproduce their own kind. Life comes only from life. This humpback whale protects its offspring.
I. Building Blocks of LifeA. Major macromolecules – composed mostly of
carbon, hydrogen, oxygen, nitrogen, phosphorus1. Water is not a macromolecule but composes approx.
2/3 of living organisms2. Carbohydrates – sugars & starches
a. Energy – energy extracted from carbs. during cellular respiration is used to produce ATP.
b. Structural – cellulose, cell wall of plants; chitin, exoskeleton of insects & arthropods
I. Building Blocks of Life3. Proteins – most varied & complex organic
moleculesa. 20 amino acids are building blocks of
all proteinsb. Structural proteins – found in cell
membranes, muscles (actin/myosin)c. Functional – enzymes (speed up reactions but are not changed by
reactionsd. Chemical messengers – hormones,
made in one part of the body but affect another part
I. Building Blocks of Life
4. Lipids – water insoluble, fats, oils, waxesa. Major component of cell membraneb. Energy storesc. Retards evaporationd. Buoyancy – marine mammals, birdse. Hormones – cholesterol; estrogen,
testosterone
B. Fuel of Life – 1. ATP – energy molecule that is used in
chemical reactions2. Photosynthesis – Fig. 4.4 – Process by
which the energy from sunlight is used to covert low energy inorganic compounds to
organic compounds
a. 6CO2 + 6H2O C6H12O6 + 6O2
b. Light energy (photons) are captured
by photosynthetic pigments, chlorophyll a is primary pigment
c. Autotrophs – make own food heterotrophs – must obtain energy from
outside sources
I. Building Blocks of Life
I. Building Blocks of Life 3. Respiration - Fig. 4.6 – process in which organic compounds are broken down to
in order to release energy a. C6H12O6 + 6O2 6CO2 + 6H2O + 36ATP
b. Energy recycles – Fig. 4.5i. Aerobic respiration – requires
O2
ii. Anaerobic respiration – no O2
required4. Primary Productivity – net gain in organic matter results when the rate of photosynthesis is greater than the rate of respiration
II. Living Machinery Organic molecules are organized into
structural & functional units
Molecules organelles cells tissues organ systems organism populations communities ecosystems
A. Cells & Organelles – the cells is the smallest unit of life, organelles within the cells are specialized for
particular tasks
II. Living Machinery 1. Prokaryotic cells – Fig. 4.7
Lack a membrane bound nucleus & membrane
bound organelles(ex - bacteria), have genetic
material; photosynthesis or chemosynthesis
takes place on the cell membrane; have a cell wall; some have flagellum for locomotion
II. Living Machinery 2. Eukaryotic cells – Fig. 4.8 Have a membrane bound nucleus
and organelles
a. Nucleus – control center b. Endoplasmic reticulum (ER) – packages organic molecules c. Golgi complex – packages &
ships d. Mitochondria – site of cell resp.
II. Living Machinery e. Chloroplasts – site of photo.f. Cell wall – protectsg. Cell membrane – regulates what
enters & leaves the cell
B. Levels of Organization – Table 4.1
Challenges of Life in the Sea
Organisms have evolved numerous adaptations that allow them to live in a wide variety of habitats – Must maintain homeostasis - planktonic – drift with currents
- benthic – live at the bottom of ocean - nekton – organisms that can swim
Challenges of Life in the Sea
A. Salinity – avg. 35% - most organisms must maintain lower body salt concentration than ocean1. diffusion – movement of molecules
down their concentration gradient; no energy required; osmosis – diffusion of water
2. osmoconformers – organisms that do not actively maintain salt and water balance, their internal concentrations change as salinity of water changes
Challenges of Life in the Sea3. osmoregulators – control the concentration
of their internal environment4. hypotonic – a solution that has a lower concentration of solutes that that of a cell
placed into it; therefore water moves into the cell
causing it to burst isotonic – concentration of solutes and
water equal that of the cell, therefore no net
movement of water hypertonic – a solution that has a higher
solute concentration than that of a cell placed
into it, therefore water moves out of the cell
Challenges of Life in the Sea5. Marine fish – have a lower salt
concentration than seawater, therefore tend to loose water; adaptations to maintain homeostasis include (Fig. 4.14)Drinks seawaterExcretes excess salt through gillsExcretes small volumes of concentrated salty
urine
Challenges of Life in the Sea5. Fresh water fish – higher salt concentration
that fresh water, therefore tend to gain water; adaptations to maintain homeostasis includeDoes not drink waterSalt absorbed by gillsExcretes large volumes of dilute urine
Challenges of Life in the Sea6. Adaptations of other
marine organismsSea turtles/sea
gulls/sea lions have glands near the eyes that excrete “salty” tears (Fig. 4-15)
Mangroves/spartina grass – excrete excess salt through leaves
Salt crystals on spartina grass
Challenges of Life in the SeaB. Temperature – most metabolic reactions proceed
faster at higher temps. (up to a point)1. Terms to describe temp. of body
a. Poikilothermy – having a body temp. that changes with that of the environment
b. Homeothermy – maintenance of a constant high body temp. & metabolic rate
2. Terms to describe where the body heat comes froma. Ectotherm – an animal that must use
environmental energy and behavioral adaptations
to regulate body temp.b. Endotherm – an animal that uses metabolic
energy to maintain a constant body temp.
Challenges of Life in the Sea
Angel Fish – poikilotherm, exothermic
Walrus – homeotherm, endothermic
Challenges of Life in the Seac. Surface area to volume ration – determines
how rapidly heat and materials flow in & out of
organisms (Fig. 4.17)- larger organisms have smaller SA/V
than smaller organisms
- smaller organisms can rely on diffusion alone
- larger organisms must rely on well developed
respiratory; circulatory, and digestive systems
IV. Perpetuating Life
A. Modes of reproduction1. Asexual – offspring are genetically identical to
parenta. Binary fission – bacteria and some
fungi; division of parent cell into 2 equal
daughter cells
b. Budding – sea anemone; division of parent cell
into 2 unequal daughter cells
2. sexual – offspring are genetically
uniquea. Gametes (sex cells)
are formed by meiosis (reduction division)
b. Fertilization – fusion of
gametes to produce a zygote
c. Zygote divides to produce
embryo
IV. Perpetuating Life
B. Reproductive Strategies1. external fertilization/external
development; fishes & frogs
- parents don’t help- large numbers of egg & sperm
released- death from disease/predation is high
IV. Perpetuating Life
2. internal fertilization/external development; birds/reptiles
- sometimes parents raise young- smaller brood sizes than fish/amp.- lower death rate than fish/amp.
3. internal fertilization/internal development; some
fish/mammals- parents play very active role in raising
young- small litters- higher survival rate
IV. Perpetuating Life
A. Evolution – theory that all species evolved from a pre-existing species; natural selection is the
process by which evolution occurs; traits are selected for or against, this results in some characteristics being passed on to future generations and some are not
B. Classifying Living Things – phylogeny is the evolutionary history of a species1. binomial nomenclature – a two named system developed by Linnaeus2. What do scientists look at when classifying?
- comparative anatomy- comparative biochemistry (DNA/RNA)- Embryology- Cytology- Fossil record
3. Taxonomic Levels – See Table 4.2
V. Diversity of Life in the Sea