Chapter 1-6

Levels of Biological Organization

biosphere, ecosystems, communities, populations, organisms, organs and organ systems, tissues, cells, organelles, molecules

Scientific inquiry

discovery science and hypothesis based science

discovery science

describes natural structures and processes

hypotheses

questions and hypothetical explanations

hypothesis must be...

testable and falsifiable

A controlled experiment...

compares experimental and control group. only the variable of interest differs between control and experimental group

Controlled experiment means...

that control groups are used to cancel effects of unwanted variables

Element

substance that cannot be broken down to other substances by chemical reactions

compound

substance consisting of two or more elements in a fixed ratio

carbon hydrogen oxygen and nitrogen

96% of living matter

Trace elements are required...

by an organism in minute quantities

Atom

smallest unit of matter that still retains the properties of an element

Subatomic Particles

Neutrons, Protons, and Electrons

Neutrons

No charge

protons

positive charge

electrons

negative charge

Atomic number

number of protons in nucleus

atomic mass

atoms total mass, sum of protons plus neutrons

isotopes

atoms that differ in number of neutrons

Chemical properties are determined by number of electrons in...

valence shell (outermost)

chemical bonds

result after interactions in atoms that stay close together

covalent bonds

pairs of electrons are shared

single bond (single covalent bond)

sharing one pair of valence electrons

double bond (double covalent bond)

share two pairs of valence electrons

nonpolar covalent bond

share electron equally

polar covalent bond

one atom is more electronegative, do not share electrons equally

Unequal sharing of electrons causes...

partial positive or negative charge for each atom or molecule

Ionic Bonds

complete transfer of (1 or many) electrons between two atoms, bonding is a result of electrostatic attraction between cation and anion

hydrogen bond forms...

when a hydrogen atom covalently bonded to one electronegative atom also attracted to another electronegative atom

The electronegative partners are usually...

oxygen or nitrogen atoms

Van der Waals interactions

attractions between molecules that are close together

Water molecule is a...

polar molecule (opposite ends have opposite charges)

Polarity allows....

water molecules to form hydrogen bonds with eachother

Four emergent properties

cohesive behavior, ability to moderate temperature, expansion upon freezing, versatility as a solvent

Hydrophilic Substance

affinity for water

Hydrophobic substance

does not have an affinity for water

Acid

any substance that increases the H+ concentration of a solution

Base

any substance that reduces the H+ concentration of a solution

Acidic

pH value less than 7

Basic

pH value greater than 7

Buffer

solution that resists change to pH

Carbon atoms can form...

diverse molecules by bonding to FOUR other atoms

Carbon chains form...

the skeletons of most organic molecules

isomers

compounds with the same molecular formula but different structure properties

Structural Isomers

different covalent arrangements of their atoms

geometric isomers

differ in arrangement about a double bond ( cis and trans isomers)

enatiomers

isomers that are mirror images of each other

All functional groups are polar except for...

methyl

carboxyl and phosphate are...

acidic

amino is...

basic

polymer

long molecule consisting of many similar building blocks

monomer

small building block molecules

dehydration reaction

when two monomers bond together through the loss of a water molecule

Hydrolysis

polymers disassemble to monomer, essentially a reverse dehydration reaction

carbohydrates

energy source, major nutrients for cells, building materials

monosaccharide

simplest carbohydrate (single sugar)

disaccharide

formed when a dehydration reaction joins two monosaccharide (double sugar)

polysaccharide

carbohydrate macromolecules. polymers composed of many sugar building blocks

starch

a storage polysaccharide of plants, consists entirely of glucose monomers

glycogen

storage polysaccharide in animals

cellulose

structural polysaccharide

lipids are...

hydrophobic

fat

energy storage

saturated fatty acids have...

maximum number of hydrogen atoms possible and NO double bonds

unsaturated fatty acids have..

one or more double bonds

phospholipid

hydrophobic tails, but phosphate group and its attachments for a hydrophilic head (major component of all cell membranes)

steroids

lipids characterized by a carbon skeleton consisting of four fused rings

cholestorol

important steroid, component in animal cell membrants

Many hormones are...

steroids produced from cholestorol

proteins have...

a wide range of function

proteins are polymers...

constructed from 20 amino acids

Amino acids are...

organic molecules with carboxyl and amino groups

amino acids differ..

in properties due to differing side chains

Sequence of an amino acid determines...

a proteins three-dimensional structure

a proteins structure determines its...

function

primary structure of a protein

unique sequence of amino acids

secondary structure

found in most proteins consists of coils and folds in the polypeptide change (a coil called an a helix and a folded structure called a B pleated sheet)

Tertiary structure

is determined by interactions among various side chains (inter actions include hydrogen bonds, ionic bonds, hydrophobic interactions, van der waals interactions and strong covalent bonds)

Quaternary structure

when a protein consist of multiple polypeptide chains

nucleic acids

store and transmit hereditary information

DNA directs...

synthesis of messenger RNA (mRNA) and through mRNA controls protein synthesis

protein synthesis

occurs in ribosomes

nucleic acids are polymers called...

polynucleotides

Nucleotides

monomers that make up each polynucleotide

Each nucleotide consists of...

nitrogenous base, a pentose sugar, and a phosphate group

nucleotide polymer

are linked together by covalent bonds, the bonds creat a backbone of sugar-phosphate units with nitrogenous bases as appendages

The two polynucleotides

are held together by hydrogen bonds forming a double helix

Nitrogenous bases in DNA pairs that form hydrogen bonds

adenine(A) always with thymine (T)
and guanine (G) always with cytosine(C)

Genetic information flow

DNA-\>RNA-\>proteien

plasma membrane

a selective barrier that allows sufficient passage of oxygen, nutrients, and waste to service the volume of every cell

nucleus

contains most of the DNA in a Eukaryotic cell

nuclear envelope

encloses the nucleus separating it from the cytoplasm

ribosomes

use information from the mRNA to make proteins

Nucleoulus

located within the nucleus and is the site of the ribosomal RNA (rRNA) syntheis

endomembrane system

regulates protein traffic and performs metabolic functions

endomembrane system components

continuous or connected via transfer by vesicles

Two distinct regions of the ER

Smooth ER (lacks ribosomes)
Rough ER (ribosomes studding its surface)

The smooth ER...

synthesizes lipids, metabolizes carbohydrates, detoxifies poison, and stores calcium

the rough ER

aids in synthesis proteins and produces new membrane

Golgi Apparatus

shipping and receiving center