BIOLOGYYYYY1.0

CET Reviewer

LEVELS OF ORGANIZATIONS

BIOSPHERE BIOME ECOSYSTEM COMMUNITY POPULATION ORGANISM SYSTEMS ORGANS

TISSUES CELLS ORGANELLES ATOMS

Unicellular organisms – perform all life functions by themselves(Nutrition, respiration, movement, excretion, growth, sensitivity, reproduction)

Multicellular organisms – has individual cells that

perform specific functions

Specialized plant cells– Root hair cell: increases water and nutrient absorption– Palisade cell: has lots of chloroplast increases the

absorption of light for photosynthesis– Epidermal: tightly packed, secretes a waxy cuticle

protects from excessive water lossSpecialized animal cells– Red blood cell: no nucleus = bi-concave shape increases

surface area: better oxygen absorption and transport– Sperm cell: with a movable tail; has lots of mitochondria

greater energy– Neuron: for interconnectivity/information transfer

through impulses sent throughout the body; has a myelin sheath that insulates the nerve fiber.

ENZYMES too!

• “biological catalysts” = changes the rate of a reaction without the enzyme being changed itself

• Combine with molecules (substrates) enzyme-substrate complex

• Enzyme reactions:– Anabolic: building up larger molecules (synthetic

reaction)– Catabolic: breaking down smaller molecules

(degradative reaction)

PHOTOSYNTHESIS• For autotrophs/producers: Light energy from the sun chemical

energy (glucose)

6CO2 + 6H2O C6H12O6 + O2

(Carbon dioxide + water Glucose + Oxygen)

• Parts:1. Light reaction: dependent on light; in the photosystems of

the thylakoid • Light energy Water oxidized to oxygen Energy: ATP and

NADPH2

2. Dark reaction (Calvin Cycle): dependent on temperature; in the stroma• ATP and NADPH2 reduce CO2 reduced carbon =

organic carbon (Glucose)

Light energy

Chlorphyll

Quick terms!

ATP = Adenosine triphosphate

NADPH2 = Nicotinamide adenine dinucleotide phosphate

The Chloroplast

Chlorophyll:– Absorbs red, violet and blue; reflects green– Most abundant forms: chlorophyll a and b– Embedded in the thylakoid

CELLULAR RESPIRATION• Sugars/carbohydrates + Oxygen ENERGY, water and carbon

dioxide

C6H12O6 + O2 6CO2 + 6H2O + Energy

• Parts: 1. Glycolosis: cytoplasm, no oxygen; glucose pyruvate2. Kreb’s Cycle/Citric Acid Cycle: inside the mitochondria; needs

oxygen

HOMEOSTASIS• Organism maintaining constant internal conditions

necessary for life• Cell and molecular physiology: – diffusion, osmosis, passive transport, active transport

• System/organ physiology: (body temp = 37/98.6 F; hypothalamus =

thermostat)– Endocrine system– Thermoregulation • skeletal muscles = shivering, • non-shivering thermogenesis: decomposing of fat

heat; sweating

–Chemical regulation • Pancreas: insulin and glucagon for

lower blood-sugar concentration• Lungs: CO2 O2; • kidneys: remove urea, adjusts the

concentration of water and ions)• Organism/ecological physiology:

Adaptation– genes change phenotypes change–extended phenotypes– reverse engineering

CELLULAR BIOLOGY• CELL THEORY: proposed by Matthias

Jakob Schleiden and Theodor Schwann–All organisms are composed of one or more

cells.–A cell is the organism’s basic unit of

structure and function.–All cells come from previously existing

cells.– The continuity of life is based on inheritable

information in the form of DNA.

TYPES OF CELLSPROKARYOTES• DNA region: nucleoid• No organelles, except

ribosomes• Locomotion (common)• Eubacteria,

Archaebacteria, Halophiles, Methanogens, Thermophiles

EUKARYOTES• With distinct nucleus• With organelles• Only some have

locomotion parts• Protoctista (Protists),

Fungi, Plantae, Animalia

PROKARYOTIC CELL

EUKARYOTIC

EUKARYOTIC

MAIN REGION: Nucleus• control center of the cell

• contains DNAPARTS FUNCTIONS

nuclear membrane selectively permeable lipid bi-layer encloses the nucleoplasm

nucleoplasm jelly-like fluid where the nucleoli and chromatin are suspended

nucleolus/nucleoli small bodies in the nucleus where ribosomes are assembled

chromatin loose network of DNA and proteins

MAIN REGION: Plasma Membrane• contains the cell contents and separates them

PARTS FUNCTIONS

tight junctions impermeable junctions; binds cells together into leak proof sheets

desmosomes anchoring junctions; prevents cells from being pulled apart

gap junctionscommunication junctions;

neighboring cells connected by connexons

MAIN REGION: Cytoplasm• cellular material outside the nucleus and inside

the plasma• site of most cellular activities

PARTS FUNCTIONS

cytosol semi-transparent liquid where organelles are suspended

inclusions non-functioning units of the cell (e.g. stored nutrients/products)

organelles metabolic machinery of the cell

MAJOR ORGANELLES WITHIN THE CYTOPLASM

• Golgi Apparatus– “traffic conductor” for cellular proteins– functions in modifying and packaging of proteins– sends out proteins for export via secretory vesicles

• Lysosome– “breakdown bodies”– contains hydrolytic enzymes that break down

proteins, carbohydrates, and lipids– also digests disease-causing bacteria

• Peroxisome– membrane sacs containing powerful oxidase enzymes– disarms dangerous free radicals by converting them

to hyrdogen peroxide• Centrioles– rod-shaped bodies– direct the formation of mitotic spindle

• Cytoskeleton– cell‘s “bones and muscles– provides an internal framework

MAJOR ORGANELLES WITHIN THE CYTOPLASM

• Rough Endoplasmic Reticulum– studded with

ribosomes– where proteins from

ribosomes assume their functional shapes

– sends proteins to the GA via transport vesicles

• Smooth Endoplasmic Reticulum– continuation of the

rough ER– functions in

cholesterol synthesis and fat metabolism

– detoxification of drugs

MAJOR ORGANELLES WITHIN THE CYTOPLASM

CELLULAR REPRODUCTIONASEXUAL SEXUAL

one parent two parents (common)Budding: plant embryonic shoot HermaphroditesFission: bacteria, paramecium,

euglena, planariahaploid gametes combine

to form diploid zygotes

Fragmentation: liverworts, sea stars

Spore formation: fungiVegetative reproduction: stolons (strawberry), tubers (potatoes),

bulbs (garlic)

CELLULAR DIVISION: Mitosis• occurs in animals and plants for growth

and repair• results in 2 identical, diploid, daughter

cells• basis for asexual reproduction in

unicellular organisms, allowing rapid population growth

CELLULAR DIVISION: MitosisTERMS DEFINITION

chromatin uncoiled DNA statechromosome coiled state, duplicate copies

chromatid single copy of the genetic materialcentromere center of chromatidskinetochore point where centromeres are attached

MITOSIS: Interphase• period between mitosis and

meiosis• divided into 3 sub phases: –G1

• preparation for chromosome or DNA replication

–S• DNA replication

–G2• preparation for mitosis or

meiosis

MITOSIS: Prophase

• centrosomes form spindle poles

• spindle fibers begin to form and are organized

• nuclear envelope disintegrates

• nucleolus disappears

MITOSIS: Metaphase

• chromosomes move to equator or metaphase plate

• sister centromeres become attached to spindle fibers from opposite poles

MITOSIS: Anaphase

• starts when kinetochores separate and chromatids move to opposite poles of the cell

MITOSIS: Telophase

• chromatids reach the poles of the cell

• nuclear envelope forms

• nucleolus reappears

CELLULAR DIVISION: Meiosis• results in four haploid, daughter cells• basis for gamete production in sexual

reproduction• as it results in halving of the chromosome

number, meiosis is also called reduction divisionTERMS DEFINITION

tetrad homologous chromosome joined together in a process called synapsis

crossing-overexchange of genetic material between homologous

chromosomescontributes to variability and diversity of organisms

CELLULAR DIVISION: Meiosis

MEIOSIS: Interphase

• “resting stage”• chromosomes are

very long and thin

• towards the end, chromosomes have already made replica chromatids joined by centromeres

MEIOSIS: Prophase I

• nuclear envelope disintegrates

• nucleolus disappears• tetrads form• crossing-over occurs

MEIOSIS: Metaphase I

• after crossing-over, homologous chromosomes move to the equator of the cell

MEIOSIS: Anaphase I

• homologous chromosomes start to separate and move to opposite poles

MEIOSIS: Telophase I

• cell divides into two daughter cells

• nuclear envelope develops

• marks the end of the first phase of meiotic division

MEIOSIS II• division of two daughter cells

from meiosis I• similar to mitosis but there is

no replication of chromosomes• results in 4 cells which are

haploid

CELLULAR DIVISION

MITOSIS MEIOSIS1 diploid

mother cell, 2 diploid

daughter cells

1 diploid parent cell, 4

haploid daughter cells

for growth and development of organism from zygote

production of gametes

for asexual reproduction in

cellular organisms

adds to genetic variability

MOLECULAR BIOLOGY• seeks to understand the molecular basis of life –

particular it relates the structure of specific molecules of biological importance to their functional role in the intact cell and organism

Genetic Code• Degenerate – many combinations correspond to a

single amino acid• Wobble position – position in the code that varies

BASE PAIRING (DNA)Adenine – ThymineGuanine – Cytosine

BASE PAIRING (RNA)Adenine – UracilGuanine – Cytosine

THE CENTRAL DOGMA

THE CENTRAL DOGMA1. REPLICATION– semi-conservative process – daughter cells would

contain one strand of the parent DNA and one strand of the new DNA

– occurs in the nucleus2. TRANSLATION– process where DNA is copied into a single

stranded RNA– occurs in the nucleus– product mRNA moves to cytoplasm

THE CENTRAL DOGMA3. TRANSLATION– occurs in ribosomes where mRNA is translated

into proteins– governed by the genetic code which combination

of three bases or triplet directs the addition of a particular amino acid to the growing protein chain

– Start and Stop Codons signals start and end of translation

** Start codons: AUG (methionine)Stop codons: UAG, UGA, UAA

GENETICS• Study of heredity (by Gregor Mendel) Mendelian Laws of Genetics and Non-Mendelian genetics• TERMS:

– Genotype: genetic make-up– Phenotype: observable properties/manifestation of genes– Allele: different forms of the gene– Dominant: property appears in heterozygous (Y)– Recessive: property masked in heterozygous (y)– Pure breeding: homozygous + homozygous breeding– Homologous chromosomes: chromosome pairs; same length and

same traits– Homozygous alleles: 2 identical alleles (YY, yy)– Heterozygous alleles: 2 different alleles (Yy)

MENDELIAN GENETICS• Characteristics are passed on from one generation to the

next by genes (factors)• Factors (genes) come in pairs (alleles)• Principles:– Principle of Segregation: Gene pairs separate during

gamete formation (PP x pp)– Principle of Independent Assortment: a

representative allele is present in the gametes (PpRr x PPrr) *dominant > recessive

• Sex-related inheritance:– Hemophilia & color-blindness (X-linked recessive)– Sex-influenced baldness

Non-Mendelian Genetics• Incomplete dominance: phenotypes in between the parental

varieties– Ie: Red x White = Pink

• Codominance: (in heterozygotes) Both alleles are expressed– Like: ABO blood groups (AB = AB type)

• Pleiotropy: 1 gene controlling more than one phenotypic trait• Polygenic Inheritance: many different genes control one

phenotypic trait (intelligence, skin color, height)• Lethal allele combination: alleles on come loci (locations)

skewed offspring ratios/missing offspring types