Exam 1 Review - Biology - PDF

**Exam 1 Review** **Chapter 1: The Study of Biology** - **Eukaryotic** cells **-** have membrane bound nucleus - **Prokaryotic** cells **-** do not have membrane bound nucleus - 3 **domains** of life - **Eukarya** -- eukaryotes - divided into three multicellular kingdoms:...

**Exam 1 Review** **Chapter 1: The Study of Biology** - **Eukaryotic** cells **-** have membrane bound nucleus - **Prokaryotic** cells **-** do not have membrane bound nucleus - 3 **domains** of life - **Eukarya** -- eukaryotes - divided into three multicellular kingdoms: Fungi, Plantae, and Animalia, and a diverse group of mostly unicellular organisms, the Protists - **Archaea** -- prokaryotes. Many are extremophiles. - **Bacteria** -- prokaryotes - **Fundamental properties of life** - **cellular organization** - All living things are composed of one or more cells - **homeostasis** - All organisms maintain constant internal conditions - **heredity** - All organisms possess genetic system that is based on replication and duplication of DNA - **energy utilization** - All organisms acquire and use energy to stay alive - **growth, development and reproduction** - All organisms are capable of growing and reproducing - The organization of the biological world is hierarchical -- each level builds on the level below it - **Cellular level** - **Organismal level** - **Population level** - **Ecosystem level** - **5 concepts unifying biology** - Life is subject to chemical and physical laws - Structure determines function - Living systems transform energy and matter - Livings systems depend on information transactions - Evolution explains the unity and diversity of life - Scientific method - A **variable** is any factor, trait, or condition that can exist in differing amounts or types - **Independent variable -** represents a quantity that is being manipulated in an experiment- What you are testing/changing? - **Dependent variable -** represents a quantity whose value *depends* on how the independent variable is manipulated -- What was the effect? - **Control variable -** quantity that a scientist wants to remain constant **Chapter 2: The Nature of Molecules** - **Atom** -- smallest unit of matter that retains all chemical properties of an element - **Nucleus** -- center of the atom, made up of protons and neutrons: - **Protons** - positive charge (+1) - **Neutrons** - neutral charge - Surrounded by orbiting **electrons** - Negative charge ( -1) - **Know how to calculate \#p, \#e, \#n** - **Atomic Number = \# Protons** - Atoms are electrically neutral - Number of protons equals number of electrons - **Atomic Mass = \# Protons + \# Neutrons** - **Ions --** atom or molecule that carries a charge **--** unbalanced - **Cation---**more protons than electrons positive charge - **Anion---**fewer protons than electrons negative charge - **Neutrons** in element may vary - Forms element with different numbers of neutrons **(isotope):** - **Isotopes** of element have **different masses** - **Valence shell** is outermost shell - Electrons in valence shell are called **valence electrons** - Atoms **most stable** when valence shell is **full** - Atoms form **chemical bonds** with other atoms to fill valence shells - **Ionic** - electron is not shared, it is completely transferred from one atom to another - **Covalent -** form when unpaired valence electrons are shared by two atoms - **Nonpolar covalent bond**: electrons are evenly shared between two atoms - **Polar covalent bond**: Electrons are shared unevenly (asymmetrical) - Electrons in polar covalent bonds spend most of their time close to nucleus of more **electronegative atom** - **Hydrogen bonds** - attraction between hydrogen atom with a partial + charge and another atom (usually oxygen or nitrogen) with partial -- charge - **Van der Waals interactions -** weak attractions or interactions between two or more molecules due to changes in electron density A table of bond and interaction Description automatically generated - Properties of water  - **Acids -** any substance that dissociates in water to increase the H^+^ concentration and lower pH (**proton donor)** - The stronger an acid is, the more hydrogen ions it produces and the lower its pH - **Bases -** substances that **acquire H^+^** during chemical reactions **(proton acceptor)** - Lowers H^+^ concentration, thus raising pH - **pH** - a measure of how acidic or basic a solution is - **Buffers** minimize changes in pH - Releasing hydrogen ions when a base is added - Absorbing hydrogen ions when acid is added - Buffers help maintain **homeostasis,** relatively constant conditions, in organisms **Chapter 3: Chemical Building Blocks of Life** - **Carbon:** - Except for water, almost all molecules found in organisms have this atom - **Hydrocarbons** -- molecule consisting only of carbon and hydrogen - Nonpolar - **Functional groups** add chemical properties - **Isomers** - Molecules with the same molecular or empirical formula but different arrangements of atoms - **Structural isomers** -- differ in the actual carbon skeleton - **Stereoisomers** -- differ in the spatial arrangement of the groups attached - **Enantiomers** -- D (right) or L (left) based on which direction rotate polarized light - **Macromolecules:** Large molecules made of smaller molecular subunits **(monomers)** joined together - **Polymer**---large number of monomers bonded together via **polymerization** (process of linking monomers together) - **Dehydration** **synthesis (condensation reaction)** - Formation of large molecules by the **removal** of water - Monomers are joined to form polymers - **Hydrolysis** - Breakdown of large molecules by the **addition** of water - Polymers are broken down to monomers - Four major classes of biological macromolecules - Carbohydrates - Lipids - Proteins - Nucleic acids - **Carbohydrates** - molecular formula **(C H~2~O)~n~** where *n* is the number of carbon atoms in the molecule - The ratio of carbon to hydrogen to oxygen is **1:2:1** in carbohydrate molecules - **Polysaccharide** - a long chain of monosaccharides linked by **dehydration synthesis** - **Energy storage** - Starch - plants - Glycogen - animals - **Structural support** - Cellulose -- plant cell wall - Chitin -- insect exoskeleton and fungi - **Proteins** - Proteins have the most diverse range of functions of all macromolecules: Enzyme catalysis, Defense, Transport, Support, Motion, Regulation, Storage - **Proteins (polymer)** are made up of **amino acids (monomer)** - Composed of **central carbon atom** bonded to: - H---hydrogen atom - N H~2~---amino functional group - C O O H---carboxyl functional group - R group---variable "side chain" - **R-group, or side chain** Represent part of amino acid core structure that makes each of 20 amino acids unique - Charged - Acidic - Basic - Polar - Nonpolar - Aromatic - Special function - **Peptide bond: C -- N** bond covalently through **dehydration synthesis** - 4 levels of protein structure - **Primary structure -** Each protein has unique sequence of amino acids - **Secondary structure - formed by hydrogen bonds between carbonyl group of one amino acid and amino group of another amino acid** - ***α*-helix** - ***β*-pleated sheet** - **Tertiary structure -** final folded shape of a globular protein - Results from interactions between residues - **Quaternary structure** - Arrangement of individual chains (subunits) in a protein with two or more polypeptide chains - **Denaturation -** change in protein shape or protein becomes unfolded completely - **Denatured** protein unable to function normally - **Nucleic acids** - **Deoxyribonucleic acid (DNA)** - **Ribonucleic acid (RNA)** - A **nucleic acid** is a polymer of **nucleotide** monomers - A phosphate group - A five-carbon sugar - A nitrogenous (nitrogen-containing) base - **Purines**---contain nine atoms in their two rings - Adenine (A) - Guanine (G) - ​**Pyrimidines**---contain six atoms in their one ring - Cytosine (C) - Uracil (U)---found only in ribonucleotides - Thymine (T)---found only in deoxyribonucleotides - Nucleic acids form when nucleotides polymerize via **dehydration synthesis** - **Phosphodiester linkage** - DNA strands are **antiparallel** - One strand runs 3′ 5′, the other runs 5′ 3′ - DNA strands form a **double helix** - The sugar--phosphate backbone faces the exterior - Nitrogenous base pairs face the interior - **Complementary base pairing:** - A - T - G -- C - **\# of purines = \# of pyrimidines** - Equal number of T's and A's; equal number of\ C's and G's - The primary structure of RNA differs from DNA: - RNA contains ribose instead of deoxyribose - 2′ --OH group on ribose is more reactive than --H - RNA is much less stable than DNA - RNA contains uracil instead of thymine - **Lipids** - diverse group of hydrocarbon compounds that are hydrophobic - **Three most important types of lipids found in cells:** - **Steroids** - Distinguished by bulky, four-ring structure - **Fats** - The primary role of fats is **energy storage** - Composed of three fatty acids linked to glycerol - **Saturated** - hydrocarbon chains consist of only single bonds between carbons - Has maximum number of hydrogen atoms - **Unsaturated** hydrocarbon chains have one or more double bonds in hydrocarbon chains - Forms "kink" in chain - **Phospholipids** - form cell membranes - **Hydrophilic "head"** - Glycerol - Negatively charged phosphate group - Charged or polar group - **Hydrophobic "tail:"** - Hydrocarbon chains **Chapter 4: Cell Structure** - **Cell theory** - **All living things are composed of one or more cells** - **The cell is the basic unit of life** - **All new cells arise from existing cells** - As a cell's size increases, its volume increases much more rapidly than its surface area - Small cells have more surface area per unit of volume than larger cells - Smaller cells have larger surface area : volume ratio - All cells share four common components: - A **plasma membrane** - an outer covering that separates the cell's interior from its surrounding environment - **Cytoplasm** - a jelly-like region within the cell in which other cellular components are found - **DNA** - the genetic material of the cell - **Ribosomes** - particles that synthesize proteins - **Prokaryotic cells** do not have membrane bound nucleus - Lack a membrane-bound nucleus - DNA is present in the **nucleoid** - Cell wall outside of plasma membrane - Contain ribosomes - No membrane-bound organelles - Two domains of prokaryotes - **Archaea** - **Bacteria** - **Flagella**---long filaments that rotate to **propel cell** - **Fimbriae**---needlelike projections that promote attachment to other cells or surfaces - **Eukaryotic cells** have membrane bound nucleus - **Know organelle functions!** An illustration shows the components of an animal cell.  - **Endosymbiosis theory** - Proposes that mitochondria and chloroplast were once free-living bacteria - Bacteria were engulfed by ancestor of modern eukaryotes but were not destroyed - Mutually beneficial relationship evolved - **Cytoskeleton** - Gives cells shape and structural stability - Transports materials within cell - 3 types of fibers: - Microfilaments (actin filaments) - Actin filaments involved in movement with **motor protein myosin** - Intermediate filaments - Microtubules - Make up **filamentous tracks** used to transport vesicles - requires a motor protein called **kinesin** - Cell-cell attachments - Tight junctions - Proteins hold adjacent cells together to form watertight seal - Desmosomes - Mechanically attaches cytoskeletons of neighboring cells - Gap junctions - Connect adjacent cells by forming channels - Plasmodesmata -- plants **Chapter 5: Membranes** - **Fluid mosaic model** - Biological membranes are a **fluid mosaic** of components - phospholipids, cholesterol, proteins, carbohydrates - in which components flow and change position, while maintaining integrity of membrane - Cellular membranes have 4 components - Phospholipid bilayer - Flexible matrix, barrier to permeability - Integral membrane proteins - Transmembrane proteins - Variety of functions such as transport and communication - Peripheral membrane proteins - Includes internal protein network for support and cell shape - Cell-surface markers - Glycoproteins and glycolipids - factors that influence fluidity/permeability - **Length** of hydrocarbon tails - **Longer = less fluid/permeable** - **Shorter = more fluid/permeable** - **Saturation** of state of hydrocarbon tails - Saturated = less fluid/permeable - Unsaturated = more fluid/permeable - Presence of **cholesterol** molecules - Less fluid/permeable - Temperature - Increase in temp = more fluid/permeable - Decrease in temp = less fluid/permeable - Membrane proteins - Transporters - Selective, allow only certain solutes to enter or leave the cell - Enzymes - Carry out chemical reactions on interior surface of plasma membrane - Cell-surface receptors - Detect chemical messages - Cell-surface identity markers - Used to identify the cell to other cells. In vertebrates, the immune system must be able to distinguish self from nonself - Cell-to-cell adhesion proteins - Proteins used to glue cells to one another - Cytoskeleton anchors - Often linked to the cytoskeleton via a linking protein - Integral membrane proteins - Span the lipid bilayer (transmembrane proteins) - Nonpolar regions of the protein are embedded in the interior of the bilayer - Polar regions of the protein protrude from both sides of the bilayer - **Diffusion - spontaneous** movement of molecules from an area of **high** concentration to **low** concentration - **Osmosis** -- net diffusion of water across a membrane toward a higher solute concentration - **Hypotonic --** Solution with **lower concentration** than inside of cell (low solute concentration outside cell) **water moves into cell** - **Hypertonic** -- Outside solution with **higher concentration** than inside of cell (high solute concentration outside cell) **water moves out of cell** - **Isotonic** -- solute concentration is equal inside and outside of cell **no net movement of water** - Facilitated diffusion - Molecules such as ions that cannot cross membrane easily may move through via proteins - Move from higher to lower concentration - No energy requirement - Channel proteins - Carrier proteins - **Passive** **transport** occurs when substances diffuse across membrane in absence of an outside energy source - Moves substances down concentration gradient - **Active** **transport** - Moves substances **against** their gradient - Requires input of energy -- ATP is used directly or indirectly to fuel active transport - **Protein pumps** - Endocytosis - Phagocytosis -- cell eating - Pinocytosis -- cell drinking - Receptor -- mediated endocytosis - Exocytosis - its purpose is to expel material from the cell into the extracellular fluid