Biology Gr.11

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182 Terms

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Genetics

The science of genes, heredity, and variation of inherited characteristics

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Chromosomes

Found within cells made of many molecules of DNA. One unique string of DNA

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DNA (Deoxyribonucleic Acid)

A molecule that carries genetic information

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Gene

A portion of “Subunit” of DNA that codes a particular trait / characteristic (One gene = One protein)

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Locus (Pl. Loci)

Where a particular gene is located on a chromosome

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Asexual Reproduction

New individual produced by a single parent through cell division

  • Genetically identical offspring

  • No need to seek a mate

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Sexual Reproduction

Individual produced through fusion of 2 sex cells

  • Genetic Variability = adaptability

  • Costly

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Mitosis

A single cell making two cells by an equal split of nucleus content

The goal of mitosis is to create 2 new genetically identical diploid (2n) daughter cells from one parent cell

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Cytokinesis

The equal split of cytoplasm and organelles contained within it

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Parent Cell - Daughter / Sister cells

The Og cell that is going to divide

The 2 cells that result from the division

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Somatic Cells

All cells except reproductive Cells

Growth, Tissue Repair, Cell Replacement

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Interphase

Growth(1) : duplication of everything except chr.

S : single stranded chr. → double stranded chr. (Two identical copies of

each (sister chromatids) are attached at the centromere)

Growth(2) : check and fix errors of S

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Prophase 1

“Prep” phase

Nuclear membrane dissolving

DNA wound around Nucleosomes

2 Copies of each Chr.

Spindle fibers form

Centrioles moving towards poles of the cell

Synapsis occurs – homologous pairs line up side by side, chromatids will cross over to exchange

genetic information (crossing over produces variability)

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Metaphase 1

“Middle” phase

Homologous pairs (tetrads) align along the equator of the cell

Spindle fibres attach to the pair of sister chromatids

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Anaphase 1

“Apart” phase

Homologs separate and move to opposite poles.

Sister chromatids remain attached at their centromeres.

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Telaphase 1

“The END”

Nuclear membrane reforms

Pairs of sister chromatids are found in each haploid daughter cell

Simultaneous with Cytokinesis

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Diploid Chr. Count

Humans : 2n=46

2 of each 23 pairs

23 sex cells

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Meiosis

Sexual reproduction (Germ Cell - Parent Cell)

The goal of meiosis is to create 4 gametes (haploid (1n) sex cells e.g. sperms, egg) from one parent cell

Each gamete cells contain different genetic information

2 divisions: (starts with 46 double stranded chromosomes (2n)

  • after 1st division - 23 double stranded chromosomes (n)

  • after 2nd division - 23 single stranded chromosomes (n)

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Allele

Different versions of the same gene

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Homologous Chr.

Pair of chromosomes containing the same gene sequence (each from one parent)

Same genes not always same alleles

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Spermatogenesis

Diploid spermatogonia → primary spermatocytes → 4 spermatids

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Oogenesis

Oogenesis → primary oocytes → 1 egg + 3 polar bodies (non-functioning reproductive cells, die over time)

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Recombination

Crossing over between homologous chr.

Occurs in prophase of Meiosis 1

Changes the Allele combination

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Independent Assortment

The homolog of one chromosome can be inherited with either hololog of the other chromosome

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Karyotypes

A photographic inventory of an individuals chrs.

22 pairs of Autosomes and 1 pair of sex chr.

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Nondisjunction

A failure in chr separation

  1. Homologous chr fail to separate during Meiosis 1

  2. Sister chromatids don’t separate during Meiosis 2

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Abnormal # of sex chr.

Extra or missing sex chr. due to nondisjunction

Does not upset the genetic balance as much as an unusual # autosomes

Offspring usually viable

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Cytoplasmic Inheritence

Sperm does not contribute mitochondria or chloroplasts to the zygote so the DNA in each of those are Maternal Inheritance

Mit / chlor not separating evanly = genetic variation

Sperm has much less cytoplasm then an egg meaning it contribute less

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Nucleotide

1.Pentose sugar (5 carbon ring)

2.Phosphate group with negative charge

3.Nitrogenous base (4 types, A=T, G=C)

Phosphate-sugar = backbone

Bases = pair up in the middle

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Law of Segregation

Members of a pair of alleles for a given trait are segregated (seperated) when gametes are formed

One allele could express itself (dominant) while the other allele is not expressed (recessive) if both

alleles are found together.

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Incomplete Dominance

One allele is not completely dominant, traits blend

Big letter (Not x) ^Subscript uppercase letter

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Codominance

Both genes in a heterozygous organism are expressed

Don’t blend but are both present

Big letter (Not x) ^Subscript uppercase letter

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Multiple Allelism

When their is more then 2 alleles for a given trait

Allows for a large number of genotypic and phenotypic possibilities

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Sex Linked Inheritance

Female XX = have two copies of X

Male Xy = have one copy of X

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Pedigree Chart

Traces the inheritance of traits among family members

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Law of Independent Assortment

when two or more characteristics are considered at one time, each pair shows dominance and segregation independently of the other

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Evolution

the relative change in the characteristics of populations that occur over successive generations

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Genetic Variation

There are different versions of genes, known as alleles, in a population which is the basis of biodiversity

Gene Pool = total of all genes in a population

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Theory of Evolution - 1

Random mutation can occur and change the DNA of an organism in a way that affects its offspring (creates new genes)

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Theory of Evolution - 2

Mutation is either beneficial, harmful, or neutral

  • If harmful, then offspring survival decreases, reproduction rates decrease ; mutation dies out and does not get passed on to the next gen

  • If beneficial, then the opposite happens

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Theory of Evolution - 3

Through reproduction, the beneficial mutation spreads. The process of eliminating bad mutations and spreading good mutations is called natural selection

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Biodiversity

the observes geographic patterns of distribution of species

  • Based on both living and fossilized species

  • Darwin found “unusual” animals on Galapagos which resembled those on the nearest land mass

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Homologous Structures

  • Similar structures in species that share a common ancestor

  • Structures that originally function one way in ancestral species become modified as they take on new functions

  • Suggest common evolutionary origins

  • E.g. All mammals have 28 skull bones, 7 neck bones!

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Analogous Structures

  • Evolved independently to have the same function

  • Suggests distant evolutionary relationship

  • i.e. Eyes/wings of insect vs. eyes/wings of bird

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Vestigial Structures

  • Type of homologous structure

  • Remnants of structures that may have had important functions in the ancestral species but has no clear function in modern descendants

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Fossils

Fossilized ancestors of animals living in the same area

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Natural Selection - Directional

selection favours individual with a more extreme variation and eliminates the rest

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Natural Selection - Stabilizing

selection acts to eliminate the both extremes from the population; the average phenotype is

favoured

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Natural Selection - Disruptive

selection eliminates intermediate types, environment can favour more then one phenotype (could end up with two species)

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Natural Selection - Sexual

the preference by one sex for certain characteristics of individuals of the other sex

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Evolutionary Change w/out Selection - Genetic Drift

change in populations allele frequency due to chance

  • smaller population, more influence

  • Loss of Diversity

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Evolutionary Change w/out Selection - Bottleneck Effect

hugh reduction in population size due to chance event

  • loss in genetic diversity

  • Rare alleles eliminated

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Evolutionary Change w/out Selection - Founders Effect

when a small, random sample of a population colonizes an area and is culturally isolated (reduces genetic variation in original population, may often lead to unique species)

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Biological Species Concept

A species is a population or group of populations whose members can breed under Natural Conditions and produce fertile offspring

Hybridization = crossbreeding between species, rare in nature

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Reproductive Isolation

inability of two organisms to reproduce due to some kind of physical or behavioral barrier

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Prezygotic Isolation

Prevention of mating or fertilization

  • Ecological ; different habitats

  • Habitat ; different habitat in the same location

  • Temporal ; different breeding seasons

  • Behavioural ; different signals or rituals for mating

  • Mechanical ; physically incompatible

  • Gamete ; sperm and egg are unable to recognize each other by their molecular markers

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Postzygotic Isolation

zygote forms but mature, reproducing offspring not produced

  • Zygote maturity ; zygotes do not develop to maturity

  • Hybrid inviability ; dies early in development

  • Hybrid infertility

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Allopatric Speciation

when 2 populations become geographically separate, mutations occur until the populations are reproductively isolated

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Sympatric Speciation

Populations in same geographical location split into separate gene pools due to genetic polymorphism ( 2 or more different phenotypes)

Often due to disruptive selection

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Adaptive Radiation

A common ancestral species evolves into multiple new species (distinct but closely related)

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Divergent Evolution

is the accumulation of differences between groups which can lead to the formation of new species

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Convergent Evolution

geographically isolated species evolve similar phenotypes due to similar selection pressures

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Coevolution

the process which one species evolves in response to the evolutionary changes in another species

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Mutualistic Relationship

symbiotic relationship in which both organisms benefit

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Antagonistic Relationship

symbiotic relationship in which one organism benefit and the other is harmed

  • Evolutionary Arms - Race : struggle between competing co-evolving genes that develop adaptations and counter - adaptations

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Commensalism

symbiotic relationship in which one organism benefits and the other is not affected

  • Mimicry : one species, the mimic, resembles another species, the model

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Phylogeny

the study of evolutionary relationships between species

  • Illustrated with a phylogenetic tree based on many different things

  • Phylogenies are based on evidence from a combination of morphological, developmental structures, biochemical, and gene sequence.

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Charecteristics of life

Growth, Reproduction, Adaptation, Movement, Metabolism, Irritability, Cells

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Components of biodiversity

  1. Diversity of genes - the total number of genetic characteristics that makeup a species; individuals in the same species have different genes

  2. Diversity of species - diversity in the different number of species (species richness)

  3. Diversity of ecosystems - the diversity of ecosystems present in the biosphere

  4. Diversity of habitats - the range of sizes, shapes, and distribution of individuals 

  5. Diversity of Interactions - the interdependent of species creates stability 

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Biodiveristy Definition

The variety and number of life forms on earth

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Taxonomy

The science of naming and classifying organisms based on similarities in structure and function

Helps identify and understand organisms

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Domains

Eukarya (Plantae, Animalia, Protista, Fungi)

  • Eukaryotes, may be unicellular or multicellular

Bacteria (Eubacteria)

  • “Ture bacteria”

  • Prokaryotes, unicellular

  • Very diverse (over 4 million), only 4000 have been classified

Archaea(Archaebacteria)

  • “Ancient bacteria”

  • Prokaryotes, unicellular

  • Lives in extreme environments (volcanoes, low oxygen, high acidity)

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Lytic Cycle

  1. Attachment of receptor site - proteins in capsid specifically fits structure of the cell wall/membrane = specific virus-hort infection 

  2. Penetration - virus injects genetic material

  3. Multiplication - Produces copies of viral genetic material and protein capsids. Transcription (duplication) of host cell DNA stops 

  4. Assembly - new viruses are assembled

  5. Lysis - release of nes viruses that infect neighbouring cells

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Lysogenic cycle

  • Viral DNA is combined with host DNA and forms a provirus (does not interfere with normal function)

  • Viral DNA can replicate along with the host cells DNA for many generations 

  • Virus is reactivated by a stimulus (stress, UV light) 

  • Re-entry into the lytic cycle

  • Ex. cold sores, chicken pox/shingles

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Characteristics of Viruses

  • Viruses are not alive

    • Do not have their own cellular organization or metabolism

    • Do not grow larger and divide, they cause the host cell to make new viruses 

  • Typically much smaller than cells

  • All are infectious

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Classifications of Viruses

  • Based of size, shape, genetic material, and their host

  • RNA and DNA surrounded by a capsid (protein coat)

  • Some have a “membrane” but this comes from the host cell - attaches as it leave the cell

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Viroids

Just RNA (no capsid), plant pathogens

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Prions

Abnormal proteins cause abnormalities in hosts protein structure (i.e. mad cow disease)

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Archaea

  • Single celled organism (unicellular) 

  • Prokaryotes

  • Cell walls lack peptidoglycan

  • Genetically different than Eubacteria

  • Can live in extreme environment

    • Methanogens : lives in low oxygen environments, produces methane gas

    • Halophiles - salty environment

    • Thermophiles - hot environment (70 - 95) 

    • Psychrophiles - cold environment (-10 - 20

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Eubacteria

  • Small 1-10 uM (bigger than Archaea)

  • Single celled organisms

  • Flagella (movement)

  • Pili (attachment to other cells or surfaces) 

  • The bacteria DNA is made of a single chromosome

  • Cell wall contains peptidoglycan (provides structure and support)

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Reproductions of Prokaryotes

  1. Asexual - Binary Fission 

  • Can divide every 15-20 minutes under favourable conditions

  • Exact replication is made

  • Individual bacterial mutations are low, but because of high reproduction rate, overall mutations for bacteria are high

  1. Sexual - Conjugation

  • Two bacterial cells come together via protein bridges where the plasmid of one cell is transferred to the other cell  

  • The cell that receiver the plasmid has a different genetic material than before 

  • This may cause the bacterial to develop traits that will davout changing conditions 

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Origin of eukaryotic cells (endosymbiosis)

  • Internal mitochondria and chloroplasts are thought to have originated from prokaryotes that were engulfed by another cell 

  • Evidence

    • They have 2 membranes

    • Inner membrane is similar the prokaryote 

    • Have this own chromosomes (circular)

    • Now “live” within another cell (mutualistic) 

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Characteristics of Protists

  • The first Eukaryotes 

  • Single celled organisms OR multicellular with cells that are all the same (seaweed) 

  • Sexual and Asexual reproduction

  • Extremely diverse in cell structure, nutrition, metabolism, reproduction and habitats (difficult to classify)

  • Key role in aquatic ecosystems

  • Many are parasitic


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Alterations of Generations

Multicellular Diploid (Sporophyte) produces haploid reproductive cells (spores) through Meiosis. A spore will undergo cell division / Mitosis to grow into a multicellular organism (Gametophyte). The Multicellular Haploid will produce gametes (sperm and eggs) which fuse to produce a diploid zygote. Which then grows into a Multicellular organism

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Characteristics of Fungi

  • Most multicellular, all heterotrophic, eukaryotes (lack chlorophyll)

  • Saprobes

    • Absorb nutrients from their environment by secreting enzymes to break down dead organic matter (decomposers) 

  • Sexual and Asexual Reproduction

  • Most fungi contain hyphae (thread like filament; when hyphae continues to branch out (asexual) leads to the development of Mycelium) 

  • Mycelium - used to absorb nutrients

  • Cell wall made of chitin (unlike cellulose in plants)

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Reproduction of Fungi

  • All fungi can reproduce Asexually

    • Budding of binary fission

    • Fragmentation

  • Some reproduce sexually through spores - Alternation of Generations

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General Characteristics of Plants

  • Multicellular eukaryotes with cell walls containing cellulose

  • Autotrophs : contain chloroplasts

  • Reproduce sexually and Asexually

  • Mostly terrestrial, variety of living conditions

Adapted for Land

  • Cuticle – waxy coating to prevent water loss

  • Stomata – open for gas exchange, close to prevent water loss

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Phylum Characteristics of Plants

  1. Bryophytes (mosses)

  • No real tissues - roots, stems, leaves

  • Produces spores

  1. Lycophytes and Pterophytes (ferns)

  • Contains conducting tissues - xylem and phloem to transport water + nutrients = taller plants 

  1. Gymnosperms (conifers)

  • Specialized reproductive structure called cones : sexual reproduction

  • Male cones (pollen cones) produce pollen grains and the female cones (egg cones) produce ovules 

  1. Angiosperm (flowers)

  • Flowering plants

  • Reproduce sexually by pollenations

  • Can self pollinate or cross pollinate by way of bird, bees, insects, wind, and water

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Characteristics of Animals

  • Multicellular, Eukaryotes (no cell wall), Heterotrophic

  • Cells can be organized into tissues (nervous and muscular tissue) 

  • Most reproduce sexually- diploid in life cycle

  • Mostly mobile

  • Uses oxygen for aerobic respiration

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No nerves ?

Porifera

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No mesoderm ?

Porifera ; No nerves

Cnidaria ; Nerves

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Protostome ?

Platyhelminthes ; reproduce by fission

Nematoda ; Parasitic

Annelida ; Segmented

Rotifera ; Small, aquatic

Mollusca ; Radula - tongue-like organ with many rows of teeth

Arthropoda ; Exoskeleton

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Deuterostome ?

Echinodermata ; No head

Chordata ; Have a notochord or supporting rod

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Common shapes and Living Arrangements for Prokaryotes (Classification)

Coccus (pl. Cocci) - round

Bacillus (pl. Bacilli) - rod shaped

Spirillum (pl. Spirilla) - Spiral

Diplo - two (Diplococcus)

Strepto - chain (Streptococcus)

Staphylo - clump (Staphylococcus)

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Plasmid

Bacteria contain small rings of DNA other than the DNA chromosomes

Plasmids are located in the cell but are not necessary for the function of bacteria

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Metabolism - Nutrition of Prokaryotes (Bacteria)

Most eubacteria are Heterotrophs

  • Parasites: absorb nutrient from living organisms

  • Saprobes: Decompose dead organic matter

Some eubacteria are autotrophs

  • Photoautotrophs : obtains energy from sunlight

  • Chemoautotrophs : obtain energy from chemical reactions

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Metabolic Rate

Rate for converting stored energy into working energy

Depends on

  • Size : larger needs more energy

  • Activity Level : Muscles burn more than fat

  • Sex : males larger (typically more muscles)

  • Age : metabolism decreases with age

  • Heredity : genetics

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Carbohydrates

Main source of energy

C,H, and O (Hydrocarbons)

3 main kinds:

  • Monosaccharide = one “base” unit (single sugar)

  • Disaccharide = two “base” units (double sugar)

  • Polysaccharides = more than two! (100s...)

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Proteins

Control Chemical reactions

Movement (muscle fibers)

Hormones - chemical messengers

Enzymes - speed up/control chemical reactions

Polymers of AAs

20 different AAs used to build proteins

12 - non essential (we make from other AAs)

8 - essential (need to eat, cannot rearrange)

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Lipids

Concentrated energy

Vitamin absorption

Cell membranes (vital)

Insulation

Hormones (ex. estrogen)

A lipid molecule usually consists of three fatty acids (Carbon/Hydrogen chains) bonded to a

“backbone” of glycerol.

  • Fats and Oils