Claim: because extant organisms share processes and structures it indicates that they evolved from a common ancestor (similarity implies ancestry). Essential.

• Claim: because extant organisms share processes and structures it indicates that they evolved from a common ancestor (similarity implies ancestry).

Essential Knowledge 1.B.1: Organisms share many conserved core processes and features that evolved and are widely distributed among organisms today.

a. Structural and functional evidence supports the relatedness of all domains.

• Structural evidence supports the relatedness of all eukaryotes. [See also 2.B.3, 4.A.2]

• To foster student understanding of this concept, instructors can choose an illustrative example such as:• Cytoskeleton (a network of structural proteins

that facilitate cell movement, morphological integrity and organelle transport)

• Membrane-bound organelles (mitochondria

and/or chloroplasts)• Linear chromosomes• Endomembrane systems, including the nuclear envelope

Evidence:

• DNA, RNA in extant organisms are all made of the same nucleotides, have same shape and structure, function in the same way; (genes are genes are genes).

• Protein synthesis, photosynthesis and respiration are similar in all organisms.

1.B.1 Evidence of Evolution Comes From Cells

• Claim: All eukaryotes have similar structures indicating they come from a common ancestor:

• Evidence: All eukaryotic cells have a cytoskeleton, membrane-bound organelles, linear chromosomes, endomembrane systems

2.B.3 – Eukaryotic Cells Maintain Internal Membranes That Partition the Cell Into

Specialized Regions

• Internal membranes facilitate cellular processes by minimizing competing interactions and by increasing surface area where reactions can occur

• Membranes and membrane-bound organelles in eukaryotic cells compartmentalize metabolic processes and enzymatic reactions– Ex. ER, mitochondria, chloroplasts, Golgi, nuclear envelope

• Archaea and Bacteria generally lack internal membranes and organelles and have a cell wall

• 4.A.2 – The structure and function of subcellular components and their interactions provide essential cellular processes – Ribosomes are small structures made of ribosomal

RNA and protein. These cellular components interact to become the sites of protein synthesis where the translation of the genetic information produces polypeptides.

• 4.A.2 cont.

• Endoplasmic reticulum occurs in two forms; rough and smooth– Rough compartmentalizes the cell. Serves as mechanical

support, provides site-specific protein synthesis with membrane-bound ribosomes and plays a role in intracellular transport.

– Smooth ER synthesizes lipids

• Golgi is membrane-bound consisting of a series of flattened membrane sacs– Functions in synthesis and packaging of material for transport

and production of lysosomes

• Mitochondria capture and transform energy– Double membrane allows compartmentalization

• Outer membrane is smooth, inner is highly folded (Cristae)• Cristae contain enzymes important to ATP production, and

increase surface area

• 4.A.2 cont• Lysosomes are membrane-bound sacs that contain hydrolytic

enzymes – Intracellular digestion, organelle recycling, cell apoptosis

• Vacuoles are membrane-bound sacs that function in intracellular digestion and release of waste products. Plant vacuoles store water, poisons, and pigments. A large centralized vacuole allows for increased surface area

• Chloroplasts are found in algae and higher plants– Structure enables it to capture light energy and convert it to

chemical bonds– Contain chlorophylls molecules (green color) which capture the

light energy. Most common is chlorophyll a– Have double outer membrane (compartmentalization). Energy

capturing reactions in the thylakoids. Thylakoids are organized into stacks called grana and produce ATP and NADPH

– Carbon fixation occurs in the stroma via the Calvin cycle

Endosymbiont Theory

Endosymbiont Theory

• Evidence:• Ribosomes• Phospholipid bilayer• Mitochondria and chloroplasts

were engulfed bacteria:– Have DNA– Semiautonomous – Binary fission– Similar in size to modern

bacteria

• Prokaryotic cells have a diameter of 1µm • Animal cells have a diameter of 10 µm • Plant cells have a diameter of 100 µm • Calculate the SA/V ratio of each and explain how

eukaryotic cells can survive even though they are considerably larger than prokaryotic cells.

• Eukaryotic organisms can attain large size by having many small cells

• Increased surface area means increased exposure to the environment.– Branching of lungs, absorption of nutrients by

intestines, filter feeding animals, loss/gain of heat (thermoregulation).

SA/V and Thermoregulation – the higher the SA/V, the more heat is lost/gained from environment

• Create compartments – Isolate competing chemical reactions (dehydration,

hydrolysis)

• Embed/hold enzymes in correct sequence– ETC – (organization = efficiency)– Enables feedback mechanisms

• Structure and function

Internal Membranes:

Nucleus

• DNA• Nuclear envelope• Nucleolus

Nucleus

DNA: – Chromatin– Chromosomes– Genes

Nucleolus

• Composed of rRNA - produces ribosomes

• May have multiple

4.A.2 - Ribosomes

• Protein synthesis• Non-membrane bound

– Prokaryotes have slightly different ribosome molecular structure (tetracycline, streptomycin)

• Free ribosomes • Bound ribosomes (ER)

2.B.3, 4.A.2 - Endomembrane System

• Phospholipid bilayer:– Nuclear envelope– ER– Golgi– Vesicles– Lysosomes– Vacuoles– Plasma membrane

Endoplasmic Reticulum (ER)

• Folded inner membrane – Increased surface

area/volume– Chemical ‘laboratories’

• Two kinds:– _______, _________

• Smooth - makes lipids, steroids phospholipids– Adrenal glands; gonads, skin oil

glands– Detoxifies poisons/drugs

• Rough ER

ER

Endomembrane System

• Vesicles

Endomembrane System - Golgi

• Produce lysosomes• Stores, modifies and sorts

products from ER• Secretion

Lysosomes

• Hydrolytic enzymes– Tay-Sachs – build up of lipids, lack of lysosomal

activity– Arthritis – release of hydrolytic enzymes

• Intracellular digestion - phagocytosis – Recycle - worn out organelles– Remodeling - metamorphosis

Endomembrane System

• Vacuole: membrane-bound sac, larger than a vesicle

• 3 types and functions:– Food vacuole - phagocytosis;

intracellular digestion– Water vacuoles - plants store

water– Contractile vacuole - ‘bladder’

Endomembrane System

• Contractile vacuole; fresh-water protozoa (paramecium)

• Excretes excess water out; osmosis constantly fills them up

Central Vacuole

• Water vacuole found in plant cells

• Tonoplast; membrane around vacuole

• Storage - minerals, water (turgor pressure), poisons

• Helps provide shape, rigidity in plant cells

Endomembrane System - Review

• 2.B.3 - Internal membranes facilitate cellular processes by minimizing competing interactions and by increasing surface area where reactions can occur

2.B.3 - Membrane-bound Organelles In Eukaryotic Cells Compartmentalize Metabolic Processes and Enzymatic

Reactions.

• Mitochondria and chloroplasts

• Peroxisomes

Energy Transducers

• Mitochondria and Chloroplasts

• Not endomembrane• Contain DNA and

ribosomes– Semiautonomous

Mitochondria• Muscle, nerve, sperm• mDNA

Chloroplasts

Peroxisomes

• Detoxification: liver cells– Use H2O2 and catalase to

breakdown alcohol

Cytoskeleton• Protein fibers in the cytosol• Functions:

– Framework and support for the cell

– Movement – within and outside

Cytoskeleton

• 3 types of proteins: – Microtubules– Microfilaments– Intermediate filaments

Microtubules

• Straight, hollow fibers (tubulin - protein)• Maintain structure, support• Move organelles within the cell• Form cilia and flagella

Microtubules • Centrosome - organelle that stores microtubules

– Microtubules form from the MTOC– Cilia and flagella– Spindle apparatus during cell division

• Centrioles: - cylindrical structures outside the nucleus; replicate during prophase; grow spindle between – Animal cells

Microfilament• Actin - Globular protein wound into a helix• Smallest molecules of cytoskeleton• Functions:

– Muscle cell contraction (along with myosin)– Cleavage furrows during mitosis– Cyclosis; cytoplasmic streaming (plants)– Elongation of pseudopodia in amoeba; macrophages

Intermediate Fibers

• Between microtubules and microfilaments• Framework• NOT dissasembled, reassembled frequently• Keratins

• 2.D.1 – All biological systems from cells and organisms to populations, communities and ecosystems are affected by complex biotic and abiotic interactions involving exchange of matter and free energy. – Ex. Cell density, biofilms, temperature, water

availability, sunlight

Biofilms • Extracellular matrix (DNA,

proteins, polysaccharides – ‘slime coat’) secreted by microorganisms (bacteria, fungi) that eventually form a mat

• Microorganisms communicate chemically to determine if there is a ‘Quorum’ of other bacteria and ‘decide’ what to do (example of: cell-to-cell communication); grow or split off to colonize other areas.