The Kingdom The Kingdom FungiFungi

• Nonmotile, filamentous eukaryotes that lack plastids and photosynthetic pigments

• Absorb nutrients from either dead or living organisms.

• Cell walls contain a matrix of chitin

• Reproduction is sexual and asexual

Mushrooms Earthball, Sclerderma aurantium

• Fungi – multicellular heterotrophs, absorb food

Aspergillus sp.Aspergillus sp.

Aspergillus sp.Aspergillus sp.

Rhizopus sp.Rhizopus sp.

RhizopusRhizopus

PenicilliumPenicillium

PenicilliumPenicillium

PenicilliumPenicillium

• Animalia – multicellular heterotrophs, “chunk” feeders, usually motile

• Plantae – multicellular autotrophs

Exploring Plant and Animal CellsExploring Plant and Animal Cells

• Eukaryote cells have extensively and elaborately arranged internal membranes that divide the cell into compartments and house enzymes for various metabolic functions

• How is the structure of these compartments maintained?

• Components of the Eukaryotic Cell

Plant cell in more detail. Figure 6.9

Animal cell in more detail. Figure 6.9

CytoskeletonCytoskeleton• Microfilaments (actin) – smallest - two strands

• Intermediate filaments – fibrous proteins supercoiled

• Microtubules – largest – hollow column

• Support – animal cells

• Motility – motor protein use microtubules as a “highway”

• Regulation – mechanical forces excerted on the cytoskeleton leads to the rearrangment other structures in the cell

MicrotubulesMicrotubules• Grow out from the centrosome – microtubule

organizing centre• Flagella and cilia are specialized arrangement

* Found in many unicellular eukaryotes, sperm, windpipe (trachea), fallopian tube etc

* Cilia – large numbers on the cell surface* Flagella – one or a few per cell* Different beating patterns

• Cilia – back and forth motion• Flagella – beating motion

* Anchored in the cell by a basal body* Microtubule doublets grip adjacent doublet through

dynein arms – these allow the movement

MicrofilamentsMicrofilaments• Made of actin protein

• 3D network just inside the plasma membrane

• Bear tension (pulling forces)* Part of the contractile apparatus of muscle cells

* Also has another protein called myosin in this instance

* Enables pseudopodia movement

• Cytoplasmic streaming – flow of cytoplasm in plant cells

Intermediate filamentsIntermediate filaments• Diverse class of cytoskeleton

• More permenant fixture

• Made of parts of the family of proteins called keratins

• Skin cells

• Reinforce cell shape and organelle position

• Nuclear lamina – lines the interior of the nuclear envelope

Nucleus and its envelopeNucleus and its envelope• Figure 6.10

• The nuclear envelope is a double membrane (two phospholipid bilayers with associated proteins) perforated by pores* It is lined by the nuclear lamina – maintains the shape

• The nucleus contains the chromosomes, made of chromatin (DNA & proteins)

• Nucleolus – a prominent structure in the nucleus where parts of ribosomes are synthesized and put together.

• Chromatin – the dense areas within the nucleus where the chromosomes are located.

Nucleus

11.4 Mitochondria11.4 Mitochondria• Mitochondria is an energy transformer of the eukaryotic

cell• Mitochondria, present in all eukaryotes, are the sites of

cellular respiration, where ATP is generated using energy from the catabolism of macromolecules – C6H12O6 + O2 CO2 + H2O + energy (energy coupling)

• Membrane-bound but not part of the endomembrane system• Each mitochondrion has its own ribosomes and DNA• Site of cellular respiration

* Outer membrane* Inner membrane – mitochondrial matrix* Cristae – infolding of the inner membrane

Some steps of cellular respiration occur in the matrix were many enzymes are located. Proteins embedded in the inner membrane function as enzymes during respiration.

Why are the cristae infolded?

Figure 6.17 – The mitochondrion site of cellular respiration

11.5 Chloroplasts11.5 Chloroplasts• Chloroplast is an energy transformer of the

eukaryotic cell• Present only in plants and algae, are the sites of

photosynthesis, where solar energy is converted to chemical energy in the form of macromolecules - CO2 + H2O + energy C6H12O6 + O2

• Membrane-bound but not part of the endomembrane system

• Has its own ribosomes and DNA• Three compartments – inner and outer membranes

and thylakoids

Chloroplasts contain the green pigment chlorophyll and are found in the cells of green plants and some photosynthetic protists.

An inner membrane system, arranged into flattened sacs and is the place where light energy is converted to chemical energy.

The fluid surrounding the thylakoids

Several stacked thylakoids

Figure 6.18 – The chloroplast, site of photosynthesis

11.6 The Endomembrane System11.6 The Endomembrane System• A network of membranes with diverse functions, connected to

each other physically or by transfer cellular products through membrane bound vesicles.

• Contains the

* nuclear envelope * endoplasmic reticulum

* Golgi apparatus

* lysosomes

* various vacuoles

* plasma membrane • A lysosome is a membranous sac of hydrolytic enzymes that

an animal cell uses to digest all kinds of macromolecules

Endoplasmic Reticulum The ER is an extensive network of

membranes that accounts for half of the total membrane in a cell

A network of membranous tubules and sacs called cisternae, it has an interior lumen continuous with the gap between the two membranes of the nuclear envelope

ER can be smooth or rough (studded with ribosomes).

Smooth ER functions include synthesis of lipids, metabolism of carbohydrates, and detoxification

Rough ER is involved in the synthesis of secretory proteins and new membrane

The Golgi ApparatusThe Golgi Apparatus• A series of flattened

membranous sacs called cisternae

• The Golgi receives products from the ER, modifies, sorts , and transports them to other parts of the cell

• Synthesizes macromolecules such as polysaccharides

• Products are received from the ER at the cis face of the Golgi, and transported away from the trans face, in transport vesicles

Movement of cellular products through the endomembrane system

Vacuoles

Contractile vacuole – used to pump excess water out of the cell.

Food vacuole – formed by phagocytosis of particulate matter

Central vacuole – mature plant cells have this large vacuole surrounded by a membrane -tonoplast. A place to store nutrients and defence compounds, acts as a disposal site for metabolic wastes, increases the membrane available to the cytosol, and enables the cell to increase in size by taking in water.

Other Differences Between Other Differences Between Prokaryotes and EukaryotesProkaryotes and Eukaryotes

• Type of cell division: binary fission in prokaryotes, meiosis or mitosis in eukaryotes

• Many linear chromosomes instead of one circular one

• Presence of a cytoskeleton to support the cell, maintain its shape, transport vesicles and chromosomes around the cell, and give the cell motility