MIDYEAR

Autosomes

non sex determining chromosomes

same between genders of a species

44 autosomes (22 pairs) in humans

Sex Chromosomes

species with single gender indiv have 2 chrom ( 1 from each parent) called sex chrom

determine gender

in humans and most of anamalia, known as X and Y

males have XY; females XX

Each parent gives 1 sex chrom to offspring

bc females only have x chrom can only contribute X

males have both so they can contribute X or Y, so it is male’s gamete that deterimes gender

also have genes that don’t determine gender.

Co Dominance

at least 2 alleles of gene are dominant to other, but not to each other

these diff allels same trait are both dominant

When both alleles are co dominant, both pheno will present seperately

each allele produce prtoein seperately- proteins not linked and both are present and can be isolated

Dominant

when 2 alleles for a trait are heterozygous, dominant allele will express its trait.

when different alleles are found in a pair, the dominant one will express its phenotype (capital letter)

Recessive

a recessive allele will only express its phenotype when paired w same allele.

will only express its phenotype in a homozygous pair.

Incomplete dominance

when alleles dfor trait are not recessive nor dominant

neither exhibit complete dominance

homozygoues geno will result in distinct phenos

but heterozygous geno will result in a pheno that is blend of 2 homo phenos

Genotype

actual alleles(genes) for a trait

Phenotype

physical or observable representation expressed by the interaction of alleles(genotype)

Alleles

alternate genes for same trait.

they produce phenotypes of a trait

manner in which they interact determine which traits will be expressed

each org gets 1 allele from parent for each trait

represented by capital letter( dominant) or lowercase letter (recessive.

Pleiotropy

1 allele affects more than 1 trait.

pleiotropic allele may be dominant for one pheno, but recessive for a nother

Law of Independent assortment

inheritance of set of alleles for 1 trait occurs independent of inheriance of another

alleles are specific for 1 trait and will not affect which alleles are inherited for another

Happens in anaphase I where tetrads are pulled into sister chromatids and sister chromatids go to random poles.

Polygenic traits

traits are often determined by more than 1 pair of alleles

means mroe than 1 protein invovled

diff alleles interact influencing/creating pheno

ex. height and skin pigmentation

Law of segregation

traits determined by 2 allels (1 from each p)

even though each parent 2 alleles, only contribute 1 per trait

bc alleles seperate from each other during anaphase II

chromatid seperate, splitting allele for trait into diff gamete

as result each gamete has 1 allele per trait

bc each parent give 1, offspring get 2 alle/trait

2 allele each individual possess segregate during gamete formation (bc meiosis) and are randomly rejoined during fertilization( 1 from each parent)

Sex linked

trait determined by gene on 1 of sex crhom (usually x)

many are recessive

bc men only have 1 x chrom, likely to inherit (therefore express) bc there is not another x chrom that carry dominant overiding allele

female have 2 x chrom, 1 x may have recessive, but other could overide with dom

Criteria of Life

-very difficult to define life

-necessary to use several criteria to determine if an organism is living or not

Integration of unifying theories

Cell theory integrated into genetic theory since cells contain genetic material (DNA and RNA) and utilizes genetic material through synthesis genetic theory is integrated with theory evolution because characteristic in genetics (alleles) varies in genes by the foundation of evolution.

Prokaryotes

-lack a nucleus and membrane bound organelles

-found in domains Bacteria and Archaea-unicellular

-possess ribosomes (for protein synthesis) that are smaller and constructed slightly differently than those of eukaryotes

-DNA is a double helix that floats in the cytoplasm as a single circular chromosome

Eukaryotes

-contain a nucleus (a membrane surrounds cell's DNA) and other membrane bound organelles

-found in domain Eukarya-functions allow eukaryotic cells to function in much more complex manner than prokaryotic cells

Metabolism

-process of obtaining energy from materials found in the environment-energy is used to maintain life processes & to make specific molecules needed to sustain life

Homeostasis

-living organisms have the ability to maintain relatively stable internal conditions, EVEN THOUGH the external environment is much different

Response

-living organisms respond to internal and external stimulus

Growth and Development

-during the lifespan of an organism, it will change in size and/or number of cells (grow) and goes through different stages of development

Adaptation

-all living organisms have mutations that may or may not be beneficial in their environment-if a mutation is beneficial, it increases an organism's chance of survival in that environment-this is adaptation and is a key component of evolution

domain archaea

-only contains prokaryotic cells-lacks a peptidoglycan cell wall (cell wall is constructed of lipids)-has introns in their genes

-utilizes methionine as the initiator amino acid for protein synthesis

-utilizes histones for the storage of DNA & has a single circular chromosome

domain bacteria

-only contains prokaryotic cells

-possess a peptidoglycan cell wall

-utilizes formyl-methionine as its initiator amino acid for protein synthesis

-has no introns in their genes-do not use histones for the organization of DNA & have a single circular chromosome

Taxonomy Levels

-domain, kingdom, phylum, class, order, family, genus, species

Three Different Ways to Define Species

-morphological: defines organisms by their physical appearance or form (morphology), however members of a species exhibit diversity regarding appearance

-ecological: organisms that are similar in appearance to one another may inhabit different niches in an environment, creating differences in their roles in an ecosystem

-phylogenic: the narrowest group of individuals that share a common ancestor, this determination uses several criteria such as morphological, behavioral, and biochemical DNA similarities

Kingdom Fungi

-eukaryotic

-multicellular

-cell wall (chitin)

-heterotrophic

Kingdom Animalia

-eukaryotic

-multicellular

-lack a cell wall

-heterotrophic

Kingdom Plantae

-eukaryotic

-multicellular

-cell wall (cellulose)

-possess chloroplasts

-photoautotrophs

viruses

-obligate parasites that infect every living species

-nonliving (pseudo-organisms)

Living characteristics of viruses

-contain genetic information (Does not contain both DNA and RNA doesnt count)

-Adapt to environment

-Reproduce (not independently)

Non living characteristics

-No cell structure

-No metabolism

-No homeostasis

-viruses dont die but can be destroyed

Three unifying theories of biology

Cell Theory, genetic theory, theory of evolution. These are the foundation of biology. do not act or exist independently, impacting, influencing each other allowing life to exist

Cell theory

A three component theory (Developed 1839-1858). 1. All living organisms are composed of one or more cells.

2. cells are unit structure, function, organization, living organisms.

3. cells arise only from pre-existing cells.

4. Cells contain genetic material (DNA and RNA) that is passed to new generations of cells through cell division

5. all cells essentially same in chemical composition

6. metabolism (transfer of energy bonds of molecules that cells can use, ATP) Biochemistry utilized by living organisms. occur only within cells.

Genetic Theory

Using mathematical analysis offspring pea plants Mendel able to deduce principles explain patterns inheritance. Mendel + Darwin independently recognized: 1. Had to be factors (genes) determined traits/characteristics

2. factors (genes) passed down from parents to offspring

3. factors (genes) vary.

They predicted genes before DNA was isolated and before it was determined traits were carried by DNA condensed chromosomes.

Theory of Evolution

Five component sequential theory that provides scientific mechanism at how life evolved from common ancestor

1. Common descent

b. variation

c. Natural selection/adaptation

d. Survival of the fittest

e. Specitiation

Common descent

all life rose from a single common ancestor that gave rise to first population

Variation

individuals within population differ. variations result of random mutations to DNA

Natural selection/adaptation

Variations more beneficial for specific environment than other variations. Individuals with beneficial variations for specific environment are more likely to survive in environment. Individuals that survive are more likely to reproduce. Very dependent on environment. A beneficial mutation in one environment can be fatal in a different environment.

Survival of the fittest

Species produce far more offspring than are needed to maintain pop. Only those who are the fittest with the most favorable adaptations, lucky to avoid death before reproducing. Survive and reproduce passing their variation to next generation.

Speciation

Over thousands of generations (Often millions of years) adaptations in pop accumulate, as these adaptations accumulate the pop. slowly changes until it becomes a "new" species

Reproduction

-creation of new generation of orgs from existing one

bc orgs have finite lifespan, populations are only to survive by reproduction.

2 types: sexual and asexual

Asexual reproduction

reprodcution w/o sex

creation of genetically identical clone/offspring from parent

usually unicellular orgs, but also seen in multicellular

binary fission

Asexual

seen in proks and unicellular euks

in proks, single chrom is copied and 2 copies go to opposite ends of cell

then cell divides

in unicellular euks, fission of parent cell into 2 daughter cells is result of cytokinesis

so, BF in unicellular euks is result of cell cycle, depending on mitosis for distribution of identical DNA

Budding

- seen in some fungi (yeast) and simple animals (cnidorians and ctenopheres)

-specific cells go through cell cycle and after cytokinesis, they are pinched off of parent organism and develop independantly from parent.

Fragmentation

some simple multicellular can have their bodies broken into many pieces (fragments)

-some, or all, may grow (using cell cycle) into complete orgs

-fragmentation is accompanied by regeneration, regrowth of body parts.

-but regen is not asexual reproduction

-seen in some species of porifera (sponges), jellyfish(cnidarians), and sea squirts (urochordata)

Sexual reproduction

genetic contribution of 2 cells resulting in new org

fusion of 2 haploid(n, containing only 1set of chrom from either mother or father) gametes(male contributes sperm, female contributes egg) creating diploid(2n, 2 sets of chrom; one from mother, other from father) zygote(fertilized egg)

Diploid (2n)

when cell possesses 2 sets of chrom, 1 set from each parent

2 copies of each chrom(1 from each parent); pairs are called homologous chromosomes

these chrom possess genes for same traits(hair color, eye color)

but exact info may differ (blue,brown eye)

humans have 46 chrom (2n=46) or 23 pairs

23 from mom 23 from dad

diff species have diff number of chroms generally

somatic cells always have diploid # of chroms

Haploid

when cell possesses half a compliment(one set) of chroms

only have 1 chrom of homologous pair

cells that are haploids are gametes

2 types of gamets: spermatazoa (male) and oocytes (female)

gametes (n) from 2 parents form zygote (2n) that will develop into multicellular org.

homologous chromosome

in somatic cells (diploid, 2n) chromosomes occur in pairs, 1 from each parent

homologous chrom are not and never were sister chromosomes/chromatids w each other

b4 meiosis, each chrom in homologous replicates and joins w its replicated chrom forming siste rchromatids/chromosome

autosomes

non-gender determining chroms

same between genders of a species

44 autosomes(22 pairs) in humans

sex chromosomes

species that have single gender individuals have 2 chrom (1 from each parent) called sex chrom

determine gender

in humans, and most of kingodm Anamalia, sex chroms are known as X and Y

males have XY;females have XX

each parent gives 1 sex chrom to each offspring

bc females only have X chrom, can only contribute X

males have both so they can contribute X or Y, so it is male’s gamete that determines gender

these chroms also have genes that dont determine gender

somatic cells ( body cells)

any cell within multicellular org except for gametes

contain full complement of chromosomes (are diploid/2n), 1 from each parent

replicate by cell cycle

Gametes

cells used for reproduction

haploid, meaning they possess only 1 set of chrom

transfer genetic info from one gen to next

Meiosis

process where ggenetic info divided among gametes,giving each gamete a haploid # of chrom

similar to mitosis, but diff

2 parts: meiosis I, meiosis II

starts with 1 diploid, ends in 4 genetically diff haploids

Phases of meisois

if an org has 3 pairs of homologous chrom (2n=6_, then each pair has 1 from mom and 1 from dad.

b4 meiosis, cell’s dna replicates

doubles# of chrom

identical chrom then conjoin into sister chromatdis

Prophase I

-chromatin condenses into chromosomes

identical chrom conjoin into sister chromatids

homologous sister chromatids conjoin into tetrads( 4 chromatids)

nuclear membrane disintegrates, centrioles move to opposite ends of the cell.

if 2n=6, 3 tetrads since 6×2/4=3

corresponding chromatids then exchange (cross over)

occurs between nonsister chromatids of tetrad

therefore DNA from parent orgs is mixed, rearranging genetic material on the chromatids

Metaphase I

tetrads line up at equator of cell and spindle fibers attach to the centromere

Anaphase I

spindle fibers contract, pulling tetrads apart

seperate into sister chromatids at seperate poles

pole that sister chromatids are pulled to is random and is reffered to as “independant assortment”

Telophase I

nucklear membrane forms around sister chromatids at each opole

sister chromatids dont unwind

cytokinesis I and telphase I occur simutaneously.

Prophase II-

nuclear membrane disintegrates, spindle fibers form

Metaphase II

sister chromatids move to equator of cell and spindle fibers attach to centromere

ANaphase II

spindle fibers contract, pulling sister chromatids apart, resulting in chromosomes being pulled to opposite ends of the cell

Telophase II

nuclear membrane form around chromsomes at each end and cytokenis II results in 4 haploid cells (gametes) with different DNA

Genetic code

living orgs depend on proteins for strucute, function and as enzymes for chem rxns that sustain life

life is impossible w/o protiens

genes - instruction for construciton of protein- are stored in DNA

genetic code is the codon (RNA)/triplet (DNA) that code for a specific amino acid and is the same for every species

means genetic code is universal

DNA contains segments known as coding and non-coding DNA

Coding DNA

DNA that codes foro construction of various types of RNA (non-protein coding DNA) and proteins (protein coding DNA)

Each segment of protein coding DNA that codes for construction of a specific protein is a gene

Non Coding DNA

DNA that codes for neither RNA nor proteins

Some DNA is ancestral DNA (gene of our ancestors that is no longer used) and remnents of viral DNA that infected either ourselves or our ancestors

Promoter region

Non coding DNA that signals location of a gene

provides a binding site for binding of RNA polymerase and allows initiation of transcription

Introns

sections within genes (Archaea and Eukarya only) dthat do not code for a protein.

seperate the protein-coding sections (exons) of a gene

introns are single or 2 repeating N2 bases

several hypthesis regaurding function/role of intron

Role of N2

genetic code is found on strands of DNA

genetic code is the order that the N2 bases occur

triplets/ codons

genetic code is broken into sequences of 3 N2 bases called a triplet (DNA) or a codon (mRNA)

each codon corresponds to a specific amino acid

since protein is made of amino acods, order of triplets/codons corresponds to order that amino acid occur in a protein

there are 64 codons/triplets (4×4×4) so each amino acid has more than one

there is a start codon/triplet that singlas beginning of instruction and 3 “stop” codons that signal end

Genes

instruction for construction of one protein is called a gene, which contains protein coding segments called exons and non-protein coding segments called introns

on DNA strand, each gene is preceeded by a promoter region

Exons

Protein coding portion of a gene

portion of gene that will be exposed

composed less than 1% of DNA

Exons within gene can be conbined in diff combonations so one gene can code for multiple proteins

introns

Non coding portion of a gene that seperates exons in a gene

may code for RNA

promoter region

non coding region of DNA that preceeds the genes that is the specific site for the binding of RNA polymerase to DNA

region where transcription is intiated

promoter regions usually 50-100 N2 bases long

of same base or 2 repeating bases

signals location of a gene

CCCCCC for Proks

TATATA for Euks

Ribonucleic acid (RNA)

similar to DNA, but 4 major diffs:

RNA uses 5 carbon sugar, Ribose instead of deoxy ribose in DNA

RNA uses urasil instead of thymine for N2 bases

RNA is single stranded (folded or twitsed)

RNA is much shorter

In some specific situations, certain types of RNA act as a catalyst since RNA is a biological molecule, considered to be enzyme even though not a protein

messenger RNA (mRNA/transcript)

template copy of one DNA gene that codes for one protein

mRNA takes this copied info from nucleuos to ribosome where protein is manufactured

Ribosomal RNA (rRNA)

type of RNA that makes up 2 subunits of ribosome

during protein synthesis, 2 subunits (made of rRNA and ribosomal protein)combine to form a ribosome

bc protein synstheiss is a complex chemical rxn and rRNA helps to regulate it, rRNA has enzymic properties and considered an enzyme

Transfer RNA (tRNA)

found in cytoplasm

interperets codons of mRNA and brings the appropriate amino acid to ribosome in order to construct polypeptide/protein

Protein synthesis

orgs can’t exist w/o proteins

proteins have many roles crucial to life-structure, transport, regulation of chem rxns

DNA holds all instructions for consturction of eveyr protein that an org needs to function

each gene is between 150-30,000 codons long

human DNA has 23688 protein producer genes and is too long and large to leave nucleus

therefore info needed for a protein needs to be transferred from DNA to mRNA to take it out of the nucleus to ribisome

2 part process: transcription, translation

transcription

occurs in nucleus and has 3 steps: binding of polymerase, synthesis of mRNA (elongation) and modification of pre mRNA

Binding of polymerase

genes on DNA (sense strand) have a promoter region - sequence of nucleotides of repeating N2 bases (CCCCC or TATATATA) that precedes a gene

-transcription factors (group of proteins) help RNA polymerase II enzyme bind to promoter region

synthesis of mRNA (elongation)

-polymerase II begins to unwind and open DNA starting at PR

Polymerase II untwists and exposes 10-20 DNA N2 bases at a time, allowing complimentary RNA nucleotides to pair

Once mRNA molecules attach to each other, growing strand of mRNA disengages from DNA and the DNA reforms

transcription begins to end after mRNA transcribes 2 termination triplets (TTATTT)

transcription continues 10-30 nucleotides b4 “pre” mRNA molecules disengage from polymerase II

occurs at 60 nucleotides/second

Often, several polymerase II molocules follow one after another on a gene, resulting in production of several mRNA strands, increasing # of proteins synthesized

Modification of pre-mRNA

mRNA must be modified after transcription and b4 it leaves through pores

after transcription, 5’ end (constructed first end) has a modified guanine (guanine cap)added which identifies the end that is to attach to the ribosome

at 3’ end total of 50-250 adenines (poly a tail) added to help prevent degredation

pre m-RNA has introns and exons, snRNP (small nuclear ribonuclear proteins) cut out introns adn w other proteins splice exons together.

creates functional mRNA molecule which exits nucleus through pores in membrane

Translation

using mRNA’s info to synthesize a protein 4 parts: initiation, elongation, translocation, termination

Initiation

5’ end of mRNA binds to small subunit of ribosome

past the guanine cap is the codon that is the start of the sequence - AUG

initiator tRNA (anticodon=UAC, amino acid = methionine) binds to mENA start sequence using H-bonds w its anticodon

major portion of tRNA briefly attaches to longer subunit

tRNA then moved slightly by ribosome

Elongation

next mRNA codon exposed

codon recognized by tRNA molecule w approptiate anticodon

an enzyme briefly attaches this next tRNA to large subunit of ribosome

another enzyme then allows for formation of peptide bond btween 1st and 2nd amino acids

ribosome then slides both amino acids over

1st tRNA seperates from amino acids (a growing polypeptide chain) leaving amino acids attached to 2nd tRNA

translocation

mRNA molecule is moved by ribosome 1 codon over

this exposes next codon

also causes first tRNA to seperate from mRNA

tRNA then returns to cytosol where it attaches to antoher amino acid (same type of amino acid given to the polypeptide)

-elongation and translocation occur concurrently and continouesly until stop codon is reached

Termination

-when stop codon(UAA, UAG, or UGA) is exposed on ribosome, a protein called “realease factor” binds to mRNA, causing polypeptide/protein to be released

2 subunits of ribosome seperate, realeasing mRNA

then polypeptide/protein spontaneously folds and twists, often w help of chaperone protein

new protein may be further modified by enzymes

Mutations

when mutations occur, they changes to DNA that can be inherited

mutations to genes cause an alteration inthe protei that is made from the gene

This may result in completedy or partially malfucntioning protein that canr esult in a genetic disease

or mutations may result in production of a variation of a protein that is not harmful or may benefit an organism (adaptation)

Note -

usually after ribosmes move past star tcodon, another ibosome attaches to mRNA (forming string of ribosomes called polyribosomes) building another polypeptide/protein. this continues mRNA begins to degrade (3 mins) takes less than 1 min to construct avg sized protein

Gene mutations

when specific nucleotide or group of nucleotides are changed or delteed or moved

results in production of wrong protein or no protein at all

generally occur when dna is being replicated b4 meiosis

point (base) mutation

when a single N2 base is impacted

3 types: substitution, insertion, deletion

insertion and deletion are known as framehsift mutations

substitution

when wrong n2 base is copied into gene triplets

results in wrong amino acid being pit n protein and may impact proteins functions

typically impacts one triplet/codon

franeshift mutations

inseertion or deletion of nucleotide (n2 base)

causes nucleotides within gene to shift

changes rest of codons and produces non-functioning polypeptide/protein

impacts many triplets/codons

causes of mutations

3 major causes: replication, carcinogen, radiation

replication

mutation that is result of mistake in replication during s phase

carcinogen

chemicals that can cause nucleotide to be added, deleted, or changed

radiation

very intense energy focused on small point

if radiation hits dna, it can shift, scramble, or delete nucleotides