Classifying Nature

(Chapter 6)

Living Things are Alike

• Common Characteristics like:

• Cells

• Tissues

• Organs

Our Study of Life

• How do our bodies work?– Physiology

• What is our place in Nature?– Ecology

• Our Bodies, like Life, are Organized!

ƒ1-2 Chapter 1 4

OH H

CH2OH

Levels ofBiological Organization I

SubatomicSubatomic ElectronElectronNeutronNeutronProtonProton

NitrogenNitrogenCarbonCarbonHydrogenHydrogen OxygenOxygen

DNADNAGlucoseGlucoseWaterWater

NucleusNucleusChloroplastChloroplastMitochondrionMitochondrion

Nerve CellNerve Cell

AtomicAtomic

MolecularMolecular

OrganelleOrganelle

CellularCellular

ƒ1-2 Chapter 1 5

Levels ofBiological Organization II

TissueTissue NervousNervousTissueTissue

BrainBrain

NervousNervousSystemSystem

PronghornPronghornAntelopeAntelope

OrganOrgan

Organ SystemOrgan System

OrganismalOrganismal

ƒ1-2 Chapter 1 6

Levels ofBiological Organization

III

PopulationPopulationHerd of PronghornsHerd of Pronghorns

HawkHawk

WaterWater

Earth’sEarth’ssurfacesurface

CommunityCommunity

EcosystemEcosystem

BiosphereBiosphere

PronghornsPronghorns

HawkHawk GrassGrass

PronghornsPronghornsSnakeSnakeBushesBushes

SoilSoilAirAir

SnakeSnake

How do we fit in?

• Where do we fit in the classification of all organisms?

• What is a classification?

• Why be classified?

• We are in the Kingdom Animalia and are Mammals!

Figure 6,1How do we fit in?

Animalia – development by means of an embryonic stageNo cell walls. Do not undergo photosynthesis

Plantae – contain a cell wall carry out photosynthesisNon-motile life stages.

Fungi - contain cell wallDo NOT photosynthesize

Protista – No cell walls reproduce by spores – motile

Monera – the bacteria: single-cell organisms

There are two major types of cells

1. Prokaryotic

2. Eukaryotic

• The eukaryotic cell is more complex and contains organelles

• The DNA of a eukaryotic cell is contained in the nucleus

Nucleus(contains

DNA) Eukaryotic cell

Prokaryotic cell

DNA(no nucleus)

Organelles

Figure 6.2Biological Evolution• First true cells were prokaryotic.

– Eukaryotic cells evolved later, followed by the other kingdoms.

Biological evolution is a change in life forms that has taken place in the past and will take place in the future.

Adaptation is a characteristic that makes an organism able to survive and reproduce in an environment.

Box 6.2 (1)

Box 6.2 (2)

Components of a Cell

Components of a Cell• Nucleus--contained within a cell by nuclear

envelope. The nucleus contains DNA.• Ribosomes--these structures make protein.• Endoplasmic Reticulum--this is a membrane

network composed RER--rough has ribosomes makes proteins, and SER--smooth makes lipids.

• Golgi Apparatus--modifies proteins involved in secretion.

• Endomembrane system--Composed of nuclear envelope, ER, Golgi, Lysosomes and Vesicles, these organelles all work together to make protein sorting and protein secretion possible.

Mitochondria are not partof the endomembrane

system • Contains its own genetic material

• Has 37 genes

• Directly passed on by your mother

• Does not change

Components of a Cell

• Mitochondria make most of our ATP!• Mitochondria have a double membrane--this

is required for ATP production.• Mitochondria have highly folded inner

membrane called cristae--this is where ATP is made.

• Mitochondria perform cellular respiration--literally cell breathing. Oxygen is used and CO2 is made. ATP is the end result.

• Fermentation occurs when there is no oxygen.

The Mitochondria • Contain their own DNA and

protein-synthesizing machinery

– Ribosomes, transfer RNAs, nucleotides.

– Thought to have evolved from endosymbiotic bacteria.

– Divide by fusion

– The DNA is in the form of circular chromosomes, like bacteria

– DNA replication is independent from DNA replication in the nucleus

The MitochondriaSite of Cellular Respiration

• This process requires oxygen.• Composed of three stages:

– Glycolysis--glucose splitting, occurs in the cell. Glucose is converted to Pyruvate.

– Krebs cycle--Electrons are removed--carriers are charged and CO2 is produced. This occurs in the mitochondrion.

– Electron transport--electrons are transferred to oxygen. This produces H2O and ATP. Occurs in the mito.

Box 6.2 (3)

The Chloroplast• Contain their own DNA and

protein-synthesizing machinery

– Ribosomes, transfer RNAs, nucleotides.

– Thought to have evolved from endosymbiotic bacteria.

– Divide by fusion

– The DNA is in the form of circular chromosomes, like bacteria

– DNA replication is independent from DNA replication in the nucleus

The Chloroplast• Membranes contain chlophyll

and it’s associated proteins

– Site of photosynthesis

• Have inner & outer membranes

• 3rd membrane system– Thylakoids

• Stack of Thylakoids = Granum

• Surrounded by Stroma– Works like mitochondria

• During photosynthesis, ATP from stroma provide the energy for the production of sugar molecules

The Plant Golgi Network

The Plant Cell wall• Cell walls are held together

by the middle Lamella.

• Made up of:

• Cellulose

• Xyloglucan

• Pectin

• Proteins

• Ca ions

• Lignin

• other ions

• Water

The Plant Cell wall• The plant cell wall is a layer of

structural material external to the protoplast, built from polysaccharides and proteins.

• The wall contains components for signaling and communication by symplastic continuity through plasmodesmata and maintains molecular connections with the plasma membrane and cytoskeleton

The Plant Cell wall• The cell wall is the organelle that

ultimately controls the shape of plant cells and consequently of organs and whole organisms.

• It is sometimes naturally strengthened and made considerably more resistant to such abuses as pathogen infection by the release of specific oligosaccharides and enzymes and by overlaying or impregnation with cutin, suberin, waxes or silica

Summary• Classification is based on similarities and

evolutionary history

• Prokaryotic cells – Have no organelles– No nucleus – one single chromosome

• Eukaryotic cells– Many organelles– Large complex genome containing many chromosomes

Summary – and thoughts for the next few weeks

• Biological evolution continues at act today in all species

• Natural selection continues to act today by both differential mortality and differential reproduction

• One frequent result of evolution within species is geographic variation

The end

Any Questions?