bio final

What makes something alive

Cellular organization
Ordered complexity
Sensitivity
Growth, development, and reproduction
Energy utilization
Homeostasis
Evolutionary adaptation

Emergent properties

Novel properties arising from the way in which components interact.

Structure determines.....

Function

Matter

Has mass and takes up space

Protons

Positively charged particles; nucleus

Neutrons

Neutral charge; nucleus

Atomic number

# of protons

Mass #

# of protons + # of neutrons

Electrons in outermost shell

Determine chemical properties

Isotopes

Atoms of a single element that possess a different number of neutrons.

Radioactive isotopes

Unstable and emit radiation as the nucleus breaks up

Half-life

The amount of time it takes for one-half of the atoms in a sample to decay

Potential energy of electron

Increases with distance from nucleus

Unfilled electron orbitals

Allow for formation of chemical bonds

Valance electrons

# of unpaired electrons in the outermost orbital

Octet rule

Atoms tend to establish completely full outer energy levels

Molecules

Groups of atoms held together by a stable association.

Compounds

Molecules containing more than one element

Stability of orbitals

Most stable when each orbital is filled

Ionic bond

Formed by the attraction of oppositely charged ions

Cation

Positive ion, loss of e-

Anion

Negative ion, gain of e-

Covalent bond

Formed when one or more pairs of valance electrons are shared by two atoms. Strong bonds, chargeless.

Single covalent

One pair of e- shared. Free rotation and increased flexibility.

Double covalent

Two pairs of e- shared. More versatility and rigid bond- no rotation.

Triple covalent

Three pairs of e- shared. Extremely rigid

Electronegativity

Atoms affinity for electrons

Differences in electronegativity

Dictate how electrons are distributed in covalent bonds

Nonpolar covalent

Equal sharing of electrons

Polar covalent

Unequal sharing of electrons

Best chem property of water

Ability to form hydrogen bonds

Cohesion

Polarity of water allows water molecules to be attracted to each other

Adhesion

An attraction between molecules of different substances

High specific heat

A large amount of energy is required to change the temp of water

High heat of vaporization

The evaporation of water from a surface causes cooling of that surface

Density of solid water is...

Less than liquid water

Water solvent

Dissolves polar molecules and ions.

Hydrophillic

Water-loving (polar)

Hydrophobic

Water-fearing (nonpolar)

Acid

Any substance that dissociates in water to increase the [H+]

Base

Substance that combines with the H+ dissolved in water, and thus increases the pH.

pH

-log[H+]

Greater [H+]

Lower pH

Lower [H+]

Higher pH

Buffers

Compounds that minimize the change in pH

Four classes of biological molecules

Carbohydrates, lipids, proteins, nucleic acids

Macromolecules

A very large organic molecule composed of many smaller molecules

Carbohydrates

monosaccharides

Nucleic acids

Nucleotides

Protien

Amino acids

Lipids/membranes

Fatty acids

Carban can form .... bonds

four

Hydrocarbons

Molecule consisting only of carbon and hydrogen. Non-polar; functional groups add chemical properties.

Versatility of carbon

Can form straight chains, branches, rings, ball, tubes, and coils

Polymers

Long molecules built by linking together similar subunits called monomers

Dehydration synthesis

Fomation of large molecules by the removal of water, monomers become polymers.

Hydrolysis

Breakdown of large molecules by the addition of water; polymers to monomers

Isomers

Molecules with the same molecular or empirical formula, but a different arrangement in space.

Structural isomers

Atoms are arranged in completely different order

Steroisomers

Atoms are arranged in the same order but differ in how groups are attached to carbon skeleton

Enantiomers

Isomers that are mirror images of each other

Carbohydrates

Molecules with a 1:2:1 ration of C, H, O

Monosaccharides

Simplest carbohydrate

Glucose

C6H12O6

Fructose

Structural isomer of glucose

Galactose

Stereoisomer of glucose

Glycosidic linkage

Covalent bond formed between two monosaccharides

Disaccharides

Two monosaccharides linked together by dehydration synthesis

Polysaccharides

Long chains of monosaccharides

Functions of carbohydrates

Energy storage and structural support

Energy storage in plants

Starch

Energy storage in animals

Glycogen

Structural support in plants

Cellulose

Structural support in arthropods and fungi

Chitin

Protein functions

Enzyme catalysis, defense, transport, support, motion, regulation, storage

Amino acids are the building blocks of

Proteins

How many different types of amino acids?

20

R is non polar

Low reactivity

R is polar

Moderate reactivity

R is charged

High reactivity

Components of an amino acid

amino group (-NH2), carboxyl group (-COOH), R group, central carbon

Peptide bond

Covalent bond formed between amino acids

Dipeptide

Formed when two amino acids are joined togther

N-terminis

amine end

C-terminis

carboxyl end

Primary stucture

Sequence of amino acids

Secondary structure

Bending resulting from H-bonds within amine and carboxyl groups in peptide backbone. Alpha helix and beta pleated sheet.

Tertiary structure

Final folded shape of a globular protein consisting of a single polypeptide chain. Further bending occurs from R group interactions.

Bonds in tertiary structure

H-bonds, hydrophobic exclusion, disulfide bridges, and ionic bonds.

Quaternary structure

Interaction and arrangement of individual chains in a protein with two or more polypeptide chains.

Motifs

Common elements of secondary structure seen in many polypeptides.

Domains

Functional units within a larger structure.
Most proteins made of multiple domains that perform different parts of the protein's function.

Chaperone proteins

Assist in folding other proteins

Denaturation

Protein loses structure and function and even unfolds completely.

Causes of denaturatoin

Changes in pH, temperature, and ionic concentration

Main characteristic of lipids

Insoluble in water

What causes lipids to be hydrophobic?

High proportion of nonpolar C-H bonds

Types of lipids in cells

Triglycerides, steroids, terpenes, phospholipids

Trigylcerides

Three fatty acids linked to a glycerol.

Steroids

Four-ring structure

Head of phospholipid

Hydrophilic (polar)

Tail of phospholipid

Hydrophobic (nonpolar)

Saturated

No double bonds

Unsatuarated

1+ double bonds

micelles

Lipid molecules orient with polar (hydrophilic) head toward water and nonpolar (hydrophobic) tails away from water

Fluid mosaic model

Structural model of the plasma membrane where molecules are free to move sideways within a lipid bilayer.

Integral protein

A type of membrane protein that is permanently attached to the biological membrane, spans the entire membrane. Nonpolar regions are embedded into interior of the bilayer. Polar regions protrude from both side of the bilayer.

Peripheral protein

A protein loosely bound to the surface of a membrane or to part of an integral protein and not embedded in the lipid bilayer.

What easily passes through the cell membrane?

Small nonpolar molecules. Small uncharged polar molecules.

What doesn't easily pass through the cell membrane?

Large uncharged polar molecules. Ions.

Osmosis

Diffusion of water through a selectively permeable membrane. From low solute concentration to high solute concentration.

Hypertonic solution

Higher solute concentration, cell wilts

Hypotonic solution

Lower solute concentration, cell bursts

Isotonic

Two solutions have the same osmotic concentrations.

Aquaporins

Specialized channels that facilitate osmosis

Functions of membrane proteins

Transporters
Enzymes
Cell-surface receptors
Cell-surface identity markers
Cell-to-cell adhesion proteins
Attachments to the cytoskeleton

Transmembrane domain

Spans the lipid bilayer
Hydrophobic amino acids arranged in α helices

Passive transport

Movement of molecules through the membrane where no energy is needed, and molecule move in response to a concentration gradient. Will continue until equilibrium is hit.

Facilitated diffusion

Movement of specific molecules across cell membranes through protein channels

Channel proteins

Have a hydrophilic channel that certain molecules or ions can use as a tunnel.

Carrier proteins

Bind to molecules and change shape to shuttle them across the membrane.

Gated channels

A protein channel in a cell membrane that opens or closes in response to a particular stimulus.

Three conditions that determine the direction of a channel proteins:

Relative concentration on both sides
Voltage differences across the membrane
Gated channels- open or closed

Saturation

Rate of transportation is limited by the number of transpoters

Active transport

Energy-requiring process that moves material across a cell membrane against a concentration difference

Active transport utilizes what type of protein

Carrier proteins

Uniporters

Moves one molecule at a time

Symporters

Moves two molecules in the same direction

Antiporters

Moves two molecules in opposite directions

Electrochemical gradient

The diffusion gradient of an ion, which is affected by both the concentration difference of an ion across a membrane and the ion's tendency to move relative to the membrane potential.

Sodium potassium pump

A special transport protein in the plasma membrane of animal cells that transports sodium out of the cell and potassium into the cell against their concentration gradients.

How many Na+ molecule and what direction?

3 Na+, OUT

How many K+ molecules and what direction?

2 K+, IN

Modern cell theory

1. All lifeforms have one or more cells.
2. Cells are the smallest living things
3. Cells arise from preexisting cells.

Cells size is limited due to...

Reliance on diffusion

Rate of diffusion is affected by...

Surface area available
Temperature
Concentration gradient
Distance

Resolution

Minimum distance two points can be apart and still be distinguished as two separate points

Light microscopes

Uses magnifying lenses with visible light.

Electron microscopes

Uses beams of electrons

Transmission electron microscope

Transmits light through the material

Scanning electron microscope

Beams of electrons onto the surface, 3D image.

Three domains of life

Bacteria, Archaea, Eukarya

Eukarya

Plantae, Fungi, Animalia, Protista

Prokaryotes

Bacteria and Archaea

Structures found in all cells

1) Nucleoid or nucleus
2) Cytoplasm
3) Ribosomes
4) Plama membrane

Prokaryote

A unicellular organism that lacks a nucleus and membrane bound organelles

Flagella

Used for locomotion, rotary motion that propels cells

Bacteria cell wall

Protects the cell, maintains its shape, prevents excessive uptke of water

Bacteria cell wall is composed of

Peptidoglycan

Archaea cell walls lack

peptidoglycan

Eukaryote

A cell that contains a nucleus and membrane bound organelles. Compartmentalization!!!

Compartmentalization

Membrane-bound organelles allow different parts of the cell to perform different functions at the same time.

Nucleus

Repository of the genetic information.

Nucleolus

Regions where rRNA synthesis takes place.

Nuclear envelope

A double membrane that surrounds the nucleus in the cell

Nuclear pores

Holes in the nuclear envelope that allow materials to pass in and out of the nucleus

Nuclear lamina

Network of fiber on inner surface, gives nuclear shape.

Chromosomes

Threadlike structures made of DNA molecules that contain the genes

Chromatin

Chromosomes + protein

Ribosomes

Makes proteins. Composed of a large subunit and a small subunit.

Free ribosomes

Synthesize proteins found in cytoplasm, nucleus, mitochondria, and other organelles

Membrane associated ribosomes

Synthesize membrane proteins, proteins to be excreted, and proteins found in the endomembrane system

Endomembrane system

Series of membrane throughout the cytoplasm

Rough Endoplasmic Reticulum

Synthesis of proteins the be secreted, sent to lysosomes, vacuoles, or plasma membrane. Has ribosomes attached.

Smooth Endoplasmic Reticulum

Carbohydrate and lipid synthesis, stores intercellular Ca2+, detoxification of foreign substances. Doesn't have many bound ribosomes. Many enzymes embedded in the membrane

Lumen

Interior of the ER

Cystol

Fluid portion of cytoplasm

Golgi apparatus

A system of membranes that modifies and packages proteins for export by the cell. Utilizes vesicles.

Cis end of Golgi

Front

Trans end of Golgi

Back

Lysosomes

Hydrolytic enzymes that catalyze the breakdown of all four types of macromolecules. Breakdown old organelles and destroys cells or foreign matter.

Peroxisome

An organelle containing enzymes that transfer hydrogen atoms from various substrates to oxygen, producing and then degrading hydrogen peroxide.

Vacuoles

Cell organelle that stores materials and maintains water balance

Tonoplast

Membrane surrounding vacuole.

Mitochondria

Biochemical processes of respiration and energy production occur. Surrounded by two membranes.

Structure of mitochondria

Outer membrane, intermembrane space, inner membrane, matrix

Redox reactions

When there is a transfer of one or more electrons from one reactant to another.

Oxidization

loss of electrons

Reduction

gain of electrons

Reduction orgo

Gain of H/ loss of O
e- move closer to atom, potential energy up

Oxidation orgo

Loss of H/ gain of O
e- move away from atom, potential energy down

ATP

Main energy source that cells use for most of their work

ATP is high energy because....

The four negative charges in its three phosphate groups repel each other.

Nicotinamide adenine dinucleotide

Acts as electron shuttles to store electrons for use elsewhere

NAD+

No electron, empty bus

NADH

Carrying electron, full bus

Aerobic respiration

Produces ATP, oxidized organic molecules, requires O2

Catabolic pathways

Breakdown of molecules and production of ATP, harvest stored chemical energy in bonds

Anabolic pathways

Synthesis of larger molecules from smaller components, typically requires energy (from ATP).

Cellular respiration

Oxidation of organic compounds using oxygen as terminal e- acceptor, regenerates ADP to ATP.

Steps for cellular respiration

Glycolysis, pyruvate processing, krebs cycle, electron transport chain

Substrate-level phosphorylation

Transfer of phosphate group directly to ADP. Occurs during glycolysis and krebs cycle.

Oxidative phosphorylation

ATP synthase uses energy from a proton gradient

Glycolysis

Breakdown of six-carbon (glucose) into two 3-C sugars pyruvate. Uses stored energy from glucose to generate some ATP and pass e- to a carrier molecule (NAD+)

First half of glycolysis

Energy input (-2 ATP)
Uses two ATP to split glucose into two 3-C molecules

Second half of glycolysis

Energy releasing (+4 ATP)
Uses existing phosphates to generate ATP and pyruvate

Net result of gylcolysis

+2 NADH, +2 ATP, and +2 pyruvate

Pyruvate processing

Coenzyme is added to pyruvate creating Acetyl CoA.
Generates more NADH and CO2.

Kreb's cycle

Complete oxidation of acetate. All energy is released from the original 6-C sugar and is converted in ATP (very little) or NADH/FADH2 (lots). More CO2 is produced.

Electron transport chain

Uses stepwise reactions to pass electrons from proteins along the inner mitochondrial membrane to create a proton gradient. Each reaction in the electron transport chain releases energy and the energy is used to pump protons across the membrane to create an electrochemical gradient.

Photosynthesis

Conversion of light energy into organic chemical energy through the reduction and fixation of CO2 into sugars.

Goal of photosynthesis

Carbon fixation.

Carbon fixation

Combining atmospheric carbon atoms to create organic molecules.

Equation for photosynthesis

CO2 + H2O + sunlight ------->(CH2O)n+ O2

Photosynthesis occurs in

Chloroplasts

Thylakoids

Flattened inner membranes of chloroplasts

Grana

Stacks of thylakoids

Stroma

Space between the thylakoids and inner membrane

Chlorophyll a

The main photosynthetic pigment in chloroplasts

Chlorophyll b

Broadens the light spectrum for photosynthesis

Carotenoids

-Accessory pigments that broaden the spectrum of colors that can drive photosynthesis.
-Absorbs blue and green light
-transmits yellow, orange, and red light

Chlorophyll structure

Porphyrin ring (magnesium in center) and hydrocarbon tail

What is in the center of a porphyrin ring?

Magnesium.

What happens to excited electrons?

Drop energy level --> fluorescence or heat
Excite electron in nearby pigment
Transferred to electron acceptor in redox rxn

Light dependent reactions

Convert electromagnetic energy into NADPH and ATP

Photosystem II

Electron excited by photon of light, replaced by extracting e- from H2O. Generates a proton gradient.

Photosystem I

Light re-excites the electron and passes it to NADP+ to create NADPH

Cyclic photophosphorylation

Used to produce additional ATP. Involves short-circuiting photosystem I to make a larger proton gradient.

ATP synthase

Will produce ATP from the proton gradient created by photosystem II.

Calvin Cycle

Converts CO2 into sugars through the energy gained in the light dependent reactions (ATP and NADPH).

Steps of Calvin cycle

1. Carbon fixation
· Carbon from CO2 added to an organic molecule
· RuBP + CO2 -> PGA
2. Reduction
· Energy is put into the molecule
3. Regeneration of RuBP
· G3P is used to regenerate RuBP

Output of Calvin cycle

Glucose is not a direct product of the Calvin cycle instead G3P a 3-carbon sugar is produced.

Ligand

Signaling molecule

Receptor proteins

Molecule to which the receptor binds

Signal transduction

Process that converts the information in the signal to a cellular response.

Direct contact

Message pass through gap junctions

Paracrine signaling

Communicating with neighboring cells

Endocrine signaling

Distant communication

Synaptic signaling

Communication between neurons

Intracellular receptors

Receptors located within the cell. Must be small and uncharged to pass into the cell

Cell surface receptors

Transmembrane proteins in contact with both the cytoplasm and the extracellular environment. Ligands cannot easily cross membrane.

Ligand gated ion channels

Will open or close depending on the ligand attached to the gate

Enzyme-linked receptor

Signaling molecule wither activates or deactivates the enzyme

GCPRs

Activated G-protein activates secondary messengers

Signal transduction either occurs by

phosphorylation or secondary messengers

Phosphorylation

·Addition of a phosphate group to change the shape of a protein
·Can activate or deactivate a protein

Protein kinase

Enzyme that adds a phosphate to a protein

Phosphatase

Enzyme that removes a phosphate from a protein

Secondary messengers

Increases the concentration of something in a cell to lead to a change in gene expression

Different types of secondary messengers

Ca+ ions, cAMP, IP3

Response to ligands binding

Will vary. Can cause a change in metabolism or gene expression

Mitosis

Division of mother cell into two identical daughter cells

Why undergo mitosis?

Asexual reproduction, growth, repair

Cell cycle

The regular sequence of growth and division that cells undergo. Two sections mitosis and interphase

G0

A nondividing state occupied by cells that have left the cell cycle, sometimes reversibly.

Differentiated cells

Reached maturity from original stem cells

G1

Growth of cellular components, duplication of organelles

S

Replication of DNA, formation of kinetochore, DNA starts to condense

G2

DNA condenses, little to no growth, production of machinery needed for mitosis

Chromosome

A threadlike, gene-carrying structure found in the nucleus. Each chromosome consists of one very long DNA molecule and associated proteins.

Chromatid

Each half of the chromosome

Sister chromatid

Identical copies of a chromosome; full sets of these are created during the S subphase of interphase.

Prophase

Migrations of things to opposite poles, Breakdown of nucleus, Spindle fibers form

Metaphase

Chromosomes line up in the middle of the cell

Anaphase

Chromosomes separate and move to opposite ends of the cell

Telophase

Chromosomes reach opposite poles and become less condensed.

Cytokinesis

Division of the cytoplasm during cell division. Membrane either pinches using actin filaments or cell plate forms then pinches in plants

G1/S checkpoint

Cell size, nutrients, DNA health, social signals (growth factors)

G2/ M checkpoint

DNA replication success, DNA health, signals to procced to mitosis

Metaphase checkpoint

Is DNA properly attached to the spindles?

DNA polymer

Nucleic acids

DNA monomer

Nucleotides

Nucleotides

Sugar, phosphate, nitrogenous base

DNA sugar

deoxyribose

RNA sugar

ribose

Purine

Double ring
Adenine or guanine

Pyrimidine

Single ring
Cytosine and Thymine

Phosphodiester bonds

Bonds between phosphate group and the 3' -OH of the next nucleotide

DNA

Encodes information for amino acid sequence of proteins

Adenine binds with

Thymine

Guanine binds with

Cytosine

DNA strands are

antiparallel

Semiconservative

Each strand is a template for new complimentary strand

Directionality of replication

Can only add bases to the 3' end of DNA

DNA polymerase

Capable of proofreading, removing mistakenly placed bases, requires a template, adds to 3' end

Helicases

Uses energy from ATP to unwind DNA

Single-strand-binding proteins (SSBs)

Coat strands to keep them apart

Supercoiling

Additional twisting of the DNA molecule caused by movement of the replication fork during unwinding

DNA gyrase

Relieves DNA supercoiling

DNA polymerase III

DNA synthesis. Adds to the 3' ends of the RNA primer

RNA primer

Short segment of RNA used to initiate synthesis of a new strand of DNA during replication

Primase

An enzyme that joins RNA nucleotides to make the primer.

Beta-clamp

Increases stability of DNA polymerase

Okazaki fragments

Small fragments of DNA produced on the lagging strand during DNA replication.

DNA polymerase I

Removes primer and replaces with DNA

Ligase

An enzyme that connects two fragments of DNA to make a single fragment. Joins Okazaki fragments.

Eukaryotic replication is complicated by

- Larger amount of DNA in multiple chromosomes
- Complex packaging
- Linear structure

Telemeres

DNA at the tips of chromosomes protects the ends

Telomerase

Enzyme that copies telomeres; composed of proteins and RNA

DNA repair

Fixes errors that occur due to replication

Mutagens

Any agent that increases the number of mutations above background level

Specific repair

Targets a single kind of lesion in DNA and repairs only that damage

Nonspecific repair

Uses a single mechanism to repair multiple kinds of lesions in DNA

Photorepair

Specific repair mechanism for one particular form of damage caused by UV light. Uses photolyase to fix a thymine dimer.

Thymine dimer

Covalent linkage between two adjacent thymine bases on exposure to ultraviolet radiation

Photolyase

Absorbs light in visible range
Uses this energy to cleave thymine dimer

Excision repair

A DNA-repair process where enzymes remove a damaged portion of DNA, synthesize a replacement section in place, and attach it to the neighboring DNA segments

Diploid

2n, two copies of each chromosome

Haploid

m, one copy of each chromosome

Germ cells

Specialized cells that go through meiosis to produce gametes

Somatic cells

All other cells, only go through mitosis

Homologous chromosomes

Chromosome partners from each parent

Sister chromatids

Two pieces of a single duplicated chromosome

Meiosis has ___ cell divisions

two

Meiosis I

Separation of homologous chromosomes

Meiosis II

Separation of sister chromatids

Purpose of meiosis is to

Produce reproductive cells

Meiosis creates _______ cells

Four

Mitosis creates _______ cells

Two

Prophase I

Chromosomes coil tighter & become visible, nuclear envelope disappears, and spindle forms

Crossing over

Process in which homologous chromosomes exchange portions of their chromatids during meiosis I.

Chiasmata

Site of crossing over

How long is the contact at chiasmata maintained?

Until anaphase I

Metaphase I

Homologues align side by side at metaphase plate and microtubules attach to each homologue.

Independent assortment

The random distribution of the pairs of genes on different chromosomes to the gametes occurs in metaphase

Anaphase I

Homologous chrmosomes move to the oppisite poles of the cell.

Telophase I

Nuclear envelope reforms around each daughter nucleus Sister chromatids no longer identical.

Meiosis II

The second phase of meiosis consisting of chromatids separating, along with the two diploid cells splitting in two

Nondisjunction

Failure of chromosomes to move to opposite poles during either meiotic division

Aneuploid gametes

Gametes with missing or extra chromosomes

Turner syndrome

Only one set of X sex chromosome. Causes underdeveloped female characterisitics.

Down's Syndrome (Trisomy 21)

Three copies of chromosome 21

Four features of meiosis

-Synapsis and crossing over
-Sister chromatids remain joined at the centromere throughout meiosis I
-Kinetochores of sister chromatids attach to same pole in meiosis I
-DNA replication is suppressed between meiosis I and meiosis II

Monohybrid crosses

Used to study two variations of a single trait.

F1 generation

First fi1lial generation. The first generation of offspring obtained from an experimental cross of two organisms, resembles the parent

F2 generation

Second filial generation. The second generation of offspring, obtained from an experimental cross of two organisms; the offspring of the F1 generation

Mendel's five-element model

1. Parents transmit discrete factors (genes)
2. Each individual receives one copy of a gene from each parent
3. Not all copies of a gene are identical
4. Alleles remain discrete - no blending
5. Presence of allele does not guarantee expression

Allele

Alternative form of a gene

Homozygous

Two of the same allele

Heterozygous

Different alleles

Dominant allele

Expressed

Recessive allele

Hidden by the dominant allele

Genotype

An individuals complete set of alleles

Pheotype

An individual's physical apperance

Principle of Segregation

During meiosis, chromosome pairs separate into different gametes such that each of the two alleles for a given trait appears in a different gamete.

Law of Independent Assortment

The law that states that genes separate independently of one another in meiosis

Medel's model assumes...

-Each trait is controlled by a single trait
-Each gene only has two alleles
-There is a clear dominant-recessive relationship between alleles

Phenotypic plasticity

Different phenotypes from the same genotype due to environmental factors.

Continuous variation

Range of possible phenotypes across genotypes; accumulation of contributions by multiple genes

Polygenic inheritance

Multiple genes are involved in controlling the phenotype of a trait

Pleitropy

An allele which has more than one effect on the phenotype

Multiple alleles

May be more than two alleles for a gene in a population; ex. blood type ABO; each individual has two alleles

Incomplete dominance

Heterozygote is intermediate in phenotype between two homozygote; blending

Codominance

Heterozygote shows some aspect of the phenotypes of both homozygotes

Epistasis

When the action of one gene obscures the effects of another gene

Pedigree analysis

An inherited trait is analyzed over the course of a few generations in one family.
Trait may be
dominant- present in every generation
recessive-may skip generations

Sickle cell anemia

A genetic disorder that causes abnormal hemoglobin, resulting in some red blood cells assuming an abnormal sickle shape. Carriers have resistance to blood-borne pathogens ex. malaria.

Sex chromosomes

Pair of dissimilar chromosomes that still pair during meiosis

XX

female

XY

male

Autosome

Non sex chromosomes

Sex linked diseases

Males at greater risk

Central dogma

DNA -> RNA -> Protein

Transcription

DNA directed synthesis of RNA. Only the template strand of DNA is used. mRNA is then used to direct synthesis of polypeptides.

RNA

All synthesized from a DNA template

mRNA

messenger RNA, brings information from the DNA in the nucleus to the cytoplasm

rRNA

ribosomal RNA; type of RNA that makes up part of the ribosome

tRNA

transfer RNA; type of RNA that carries amino acids to the ribosome

snRNA

small nuclear RNA

SRP RNA

signal recognition particle RNA, part of SRP that recognizes the signal peptides of polypeptides targeted for completion on ER

miRNA

micro RNA; a class of functional RNA that regulates the amount of protein produced by a eukaryotic gene

Codon

Block of 3 DNA nucleotides corresponding to an amino acid

Start codon

Codon that signals to ribosomes to begin translation; codes for the first amino acid in a protein

Stop codon

codon that signals to ribosomes to stop translation

Template strand

The strand that is used as a template during transcription

Coding strand

The complementary strand

Open reading frames

String of codons uninterrupted by a stop codon

Transcription unit

Portion of gene that is copied into RNA

Prokaryotic transcription

Does not require a primer
Requires:
Promoter
Start site
Termination site

3 phases of transcription

initiation, elongation, termination

Promoter

Specific region of a gene where RNA polymerase can bind and begin transcription. It is not transcribed.

Elongation

RNA nucleotides are added to the chain

Transcription bubble

Contains RNA polymerase, DNA template, and growing RNA transcript

After transcription bubble

Now transcribed DNA is rewound as it leaved the bubble

Termination

Signal stops and the transcription bubble dissociates and DNA rewinds.

Hairpin loop

GC-rich sequence in prokaryotes that RNA polymerase recognizes to terminate transcription

What is coupled in prokaryotes?

transcription and translation

Operon

Group of genes operating together

Eukaryotic transcription

occurs in the nucleus under the direction of three forms of RNA polymerases.

RNA polymerase I

transcribes rRNA

RNA polymerase II

transcribes mRNA

RNA polymerase III

transcribes tRNA

Imitation in eukaryotes

Requires a series of transcription factors. Necessary to get the RNA poly II to initiate the gene expression.

Addition of 5' methyl G cap

Protects from degradation, involved in translation initiation

Addition of 3' poly-A tail

Created by poly-A polymerase; protection from degradation

Removal of non-coding sequences (introns)

Pre-mRNA splicing done by spliceosome

Introns

Non-coding sequences of DNA

Exons

Sequences that will be translated

Splicosome

An enzyme that splices introns out of RNA. Formed from snRNP cluster with other proteins.

Alternative splicing

Splicing of introns in a pre-mRNA that occurs in different ways, leading to different mRNAs that code for different proteins. Increases the diversity of proteins.

Transcriptome

All the RNAs produced from a genome.

Protrome

All the proteins produced from a genome

Aminoacyl-tRNA synthetase

Adds amino acids to the acceptor stem of tRNA

Charged tRNA

A transfer RNA molecule to which the appropriate amino acid has been attached via the energy from ATP.

Ribosomes

Decodes the mRNA and forms polypeptide bonds.

E site

Binds the tRNA that carried the previous amino acid added.

P site

Binds the tRNA attached to the growing polypeptide chain.