Fundamentals of Biology

4.1 The Ingredients of Life

• A. The Building Blocks• 1 Organic compounds – molecules containing

C, H, & O• Make life possible• High-energy molecules Energy used to synthesize Energy released in breakdown• Four types of organic compounds

2 Carbohydrates – sugars

• Glucose – metabolized for energy• Starches – long chains of simple sugars used

for energy storage• Chitin – skeletal material• Cellulose – cell structure

3 Proteins

• Chains of amino acids• Muscles are mostly made up of proteins• Enzymes – catalyze reactions• Structural proteins – skin, hair, skeleton• Hormones

4 Lipids

• Fats, oils, & waxes• Energy storage – more than twice as much as

sugar• Water repellant• Buoyancy• Insulation• Hormones

5 Nucleic Acids• Store and transmit the genetic information of

all living things• Long chains of subunits called nucleotides• DNA – instructions for the construction and

maintenance of an organism; the complete set is called the genome

• The nitrogen bases are sequenced into genes that code for a specific protein

• RNA – helps DNA

B. The Fuel of Life

• ATP – the molecule used to store energy; like a rechargeable battery

• You use ~ 125 lbs./day• Organisms need to capture, store and use

energy• Most organisms use only two sets of reactions

1 Photosynthesis: Making the Fuel

• Algae, plants, and some microorganisms• Capture the sun’s energy and use it to make

glucose The pigment chlorophyll captures the solar energy CO2 + H2O → C6H12O6 (glucose) + O2

• We rely on photosynthesis for food and oxygen• Organisms that photosynthesize are called

autotrophs Plants on land; bacteria and algae in the ocean

2 Respiration: Burning the Fuel

• Both autotrophs and heterotrophs do it• Releases the energy from org. compounds• Reverse of photosynthesis Organic matter (glucose) + O2→ H2O + CO2

• Similar to burning wood or oil• Chemical energy captured in ATP• Aerobic – uses oxygen, more efficient• Anaerobic – does not use oxygen, less

efficient

3 Primary Production

• Most of the glucose is used for fuel or converted into other types of org. compounds

• The organic matter autotrophs make is called primary production

Used by the organism for growth and reproduction

• Autotrophs are also called producers

4 The Importance of Nutrients• Vitamins, minerals and other substances are

needed to convert glucose into other org. compounds

• Nitrogen for proteins & nucleic acids• Phosphorus for nucleic acids• Silica (SiO2) to make shells• Iron – necessary, but a limited resource in the

ocean

4.2 Living Machinery

• Organic compounds are organized into functional units that are alive

A. Cells and Organelles

Cell – basic unit of life All organisms are made of cells Wrapped in a cell membrane• Cell is filled with jelly-like cytoplasm• Organelles have specific jobs in the cell

1. Structurally Simple Cells: Prokaryotes

Prokaryotes are primitive cells Ancient, simple, small No membrane-bound organelles Bacteria

Prokaryotes have few structures: Cell wall – support Ribosomes – assemble proteins DNA – loose in the cytoplasm Flagella – locomotion

2. Structurally Complex Cells: EukaryotesEukaryotic cells are organized and complex

Larger than prokaryotesHave specialized organelles:

Nucleus – contains chromosomes (DNA) Endoplasmic reticulum – make proteins and other org.

molecules for the cell Golgi apparatus – package and transport molecules Mitochondria – respiration center to provide energy Flagella and cilia – for movement

Only in plant & algal cells Chloroplasts – photosynthesis center Cell wall - support

B. Levels of Organization1. A cell is self-contained and can carry out all the functions

necessary for life• Unicellular – all prokaryotes and some eukaryotes• Multicellular – most eukaryotes Human body has 100,000,000,000,000 cells• In multicellular organisms cells specialize to perform different

tasks for the organism• Cells that act together for a specific job are called tissues Muscle, nervous, bone, blood, epithelial• Tissues are organized into organs to carry out specific functions Liver, kidney, heart, skin, brain• Organs act together in an organ system Skeletal, muscular, excretory, endocrine, digestive

2. Organization exists outside the individual organism

Species – one type of organism Blue mussel Population – a group of one species A bunch of blue mussels Community – several different populations that live and

interact in an area Blue mussels, crabs, barnacles, & chitons living on a rock Ecosystem – the communities living together with the

physical environment Living on a rocky shore with seawater, air, temperature,

sunlight, etc.

4.3 Challenges of Life in the Sea

• Marine organisms must cope with different problems than on land

• They have evolved ways to adapt to their marine habitat

• Most important is maintaining homeostasisKeeping their internal condition normal

regardless of the external condition

A. Salinity

• Marine organisms are immersed in a medium – sea water – that can greatly affect their cell function

• Enzymes and organic molecules are sensitive to ion concentration (salinity)

1. Diffusion and Osmosis• Dissolved ions move around in water• Random movement spreads them out in an even

distribution• Results in diffusion – movement from high low

concentration• When concentrations are different inside and outside

a cell, substances will move in/out by diffusion Salt from seawater will diffuse into the cell Nutrients will diffuse out of the cell• The cell membrane blocks block diffusion It’s selectively permeable – it allows only some

substances to go in/out

• Water is a small molecule and can fit through the cell membrane

It also diffuses from high → low concentration If a cell has more solutes inside than outside, water will

stream in and swell the cell If the seawater has more salt, water will leave and the

cell will shrivel This diffusion of water is called osmosis• Cells may need to move materials against diffusion (low

high) e.g. expelling extra salt or taking in more sugar Active transport – proteins in the cell membrane pump

materials using ATP1/3 of the cell’s energy is spent on this

2. Regulation of Salt and Water Balance• Marine organisms have adapted ways to balance water and

salt• Osmoconformers –their internal concentrations change with

the salinity of the seawater Live in a narrow range of salinity• Osmoregulators – control internal concentrations to avoid

osmotic problems Can tolerate changes in salinity better Can change their internal concentrations to match the

seawater Salt water fishes lose water by osmosis Drink water or reduce urine amount to replace lost

water Excrete excess salts in the urine or through the gills

Freshwater fishes gain water by osmosisDon’t drink water or produce lots of urineSalt absorbed by gills Some marine birds and reptiles have special

glands to get rid of excess salt Most algae have rigid cell walls that resist the

swelling caused by osmotic water gain

B. Temperature

Metabolic reactions speed up/slow down when temperature goes up/down

Metabolic rate doubles every 10oC At extreme temps most enzymes cease to

function Marine organisms are adapted to live in a

temp range Thus determining what regions of the oceans

they live

Ectotherms – “cold blooded” lose their heat to the seawater

Endotherms – “warm blooded” retain heat and keep their body temp higher than the water

Mammals, birds, and some large fishes Poikilotherms – body temp changes with the temp of the

seawater Incl. all ectotherms & endothermic fishes Homeotherms – keep internal temp the same, regardless

of outside temp Produce more heat as need to keep their metabolic

activity high Mammals & birds They need to eat more food Insulate their bodies with feathers, hair, and blubber

C. Surface-to-Volume Ratio

Heat and materials exchange across the surface of an organism

The surface-to-volume ratio (S/V ratio) determines how rapidly this happens

As organisms get larger the volume grows faster than the surface area

Small organisms rely on diffusion Large organisms respiratory and excretory

systems

4.4 Perpetuating Life

A species must reproduce or vanish from the planet

Produce a new offspring Pass on the genetic information

A. Modes of Reproduction

Cells reproduce through cell division Cell fission in prokaryotes; mitosis in

eukaryotes Results in identical daughter cells

1. Asexual Reproduction

No partner Offspring are genetically identical – clones Most single-celled organisms reproduce this way Some multicellular organisms do: Some sea anemones will split in half, making two

smaller ones–fission

Some sponges develop growths that break off to become separate individuals – budding or vegetative reproduction

2. Sexual Reproduction Union of two separate gametes from two parents Ovaries – female gonads that produce eggs Testes – male gonads that produce sperm Meiosis divides the chromosomes in half; Fertilization

combines them to form a full set again A fertilized egg is called a zygote. It has DNA from both parents This genetic recombination causes variation in the offspring Greatest advantage of sexual reproduction The zygote divides by mitosis and eventually forms an embryo May pass through a larval stage on the way to adulthood

B. Reproductive Strategies

The goal of reproduction is to pass on the genes Varying reproductive strategies to get the same

result Broadcast spawning – release millions of eggs and

sperm into the water No parental care, most die Have few offspring and invest more time and

energy into their survival Some use sexual and asexual reproduction Some species are hermaphroditic, both sexual

organs

4.5 The Diversity of Life in the Sea

• The vast diversity of organisms in the ocean came through millions of years of evolution

• The gradual alteration of a species’ genetic makeup

A. Natural Selection and AdaptationIndividual organisms show variation in how they: Find food, avoid being eaten, reproduce, find mates,

metabolize, etc. The best-adapted produce more offspring than the

others This process is called natural selection As their genes get passed on the favorable traits

become more common The population’s genetic makeup changes over time as

it adapts to its environment Populations either adapt to the changes in the

environment or become extinct

B. Classifying Living Things

To discuss the huge variety of life forms we must first classify them

1. The Biological Species Concept What is a species? A type of organism? A population with common characteristics

that can successfully breed with each other (fertile offspring)

If two populations cannot interbreed they are reproductively isolated

2. Biological Nomenclature• Organisms are identified with a two-word

name - Genus and species• Blue whale – Balaenoptera musculus• Fin whale – Balaenoptera physalus• Minke whale – Balaenoptera acutorostrata• Latin or Greek is used for naming• Common names are confusing, scientific

names are used worldwide to precisely identify a species

Levels of Classification

Domain Kingdom Phylum Class Order Family Genus Species

3. Phylogenetics: Reconstructing Evolution

Organisms are grouped according to their relatedness

Related organisms share an evolutionary history, or phylogeny

They share a common ancestor Look at fossil record, anatomy, reproduction,embryological development, DNA, behavior,

etc.

4. The Tree of Life

• Classifications have changed over time• Started with two kingdoms – Animalia and

Plantae• Then five kingdoms – added Fungi, Monera, &

Protista• Then three domain system