Ch 3 - Ch 5 Concepts Flashcards
4 classes of biological molecules
Carbohydrates, proteins, lipids, nucleic acids
2 sugar classifications based on location of carbonyl group
Aldose - carbonyl is terminal
Ketose - carbonyl is internal
Disaccharide
2 sugars linked by glycosidic linkage
Polysaccharides
storage and structural
determined by its sugar monomers and position of glycosidic linkages
Starch
Plant storage
surplus in granules within chloroplasts and other plastids
alpha glucose
Glycogen
storage in animals
liver and muscle cells
Cellulose
plant wall
polymer of glucose
beta glucose
Chitin
structural polysaccharide
exoskeleton of arthropods
structural support for cell walls of many fungi and bacterial spores
Lipids
do not form polymers
hydrophobic
non-polar covalent bonds
Lipids (types)
fats
phospholipids
steroids
Fats
constructed of glycerol and fatty acids
major function is energy storage
Saturated fatty acid
maximum # of hydrogen atoms possible and no double bonds
solid at room temp
most animal fats
Unsaturated fats
have one or more double bonds
liquid at room temp
usually plant fats and fish fats unsaturated
Hydrogenation
Process of converting unsaturated fats to saturated fats by adding hydrogen
creates partial saturated and unsaturated fats with trans double bonds
Phospholipid
2 fatty acids (tail) and a phosphate group (head)
Cholesterol
a steroid
component in animal cell membranes
Steroids
lipids characterized by a carbon skeleton consisting of 4 fused rings
Proteins (% mass of most cells?)
account for more than 50% of the dry mass of most cells
Proteins (functions
- structural support (keratin, collagen, elastin)
- storage (store amino acids - ovalbumin, casein)
- transport (hemoglobin, cytochromes)
- cellular communications (receptors and ligands)
- movement (Actin and myosin)
- defense against foreign substances (antibodies)
Enzymes
Speed up chemical reactions by lowering the activation energy needed
Metabolism
all chemical reactions occurring in the body
Polypeptides
polymers built from the same set of 20 amino acids
a protein consists of one or more polypeptides
Amino acids
organic molecules with carboxyl and amino groups
differ in their properties due to differing side chains, R-groups
linked by peptide bonds
Functional protein
consists of one or more polypeptides twisted, folded, and coiled into a unique shape
4 Levels of Protein Structure
primary - sequence of amino acids (genetically inherited info)
secondary - found in most, coils and folds (alpha helix, beta pleated sheet)
tertiary - determined by R-groups interactions (all the bonds; disulfide bridges may reinforce)
quaternary - results when a protein consists of multiple polypeptide chains
Collagen
fibrinous protein consisting of 3 polypeptides coiled like a rope (ex of quat structure)
Hemoglobin
globular protein consisting of 4 polypeptides: 2 alpha and 2 beta chains (ex of quat structure)
Sickle-cell disease
single amino acid substitution (Gluy to Val) in hemoglobin
glutamic acid is neg and valine is neutral, changes shape of molecule
X-ray Crystallography
used to determine a protein’s structure
Nuclear Magnetic Resonance (NMR)
another method to determine protein structure that does not require protein crystallization
uses magnetic properties
Types of Nucleic Acids
Deoxyribonucleic acid (DNA)
Ribonucleic acid (RNA)
DNA
provides instructions for its own replication
directs synthesis of mRNA
mRNA goes on to control protein synthesis (in ribosomes)
Nucleic acids
polymers called polynucleotides
made of nucleotides (monomer)
Nucleotide
nitrogenous base (G, A, T, or C), pentose sugar, and a phosphate group
portion of the nucleotide without the phosphate group is called a nucleoside
Pure As Gold
Purine Adenine Guanine
2 n’s = 2 rings
Double Helix
Watson and Cric in 1953
reinterpreted Roselyn Franklyn’s data
proved Pauling wrong
Nitrogenous Bases
Pyrimidines (cytosine, thymine, and uracil), have a single six-membered ring
Purines (adenine and guanine), have a six-membered ring fused to a five-membered ring
Nucleotide
nucleoside + phosphate group
Polynucleotide
nucleotide polymers linked together
linked by OH- group on the 3 prime carbon of one nucleotide and the phosphate on the 5 prim carbon on the next
DNA molecule
has 2 polynucleotides spiraling around an imaginary axis forming a double helix
antiparallel
Cell theory
All cells are related by their descent from earlier cells
Cell structure
correlated to cell function
Light Microscope
can magnify 1, 000 times the size of the actual specimen
image is upside down and backward
Cell fractionation
enables scientists to determine the functions of organelles
separates by size and density
All cells basic features
- plasma membrane
- semi-fluid substance called cytosol
- chromosomes
- ribosomes
Prokaryotic cells
- no nucleus
- DNA in unboud region (nucleoid)
- No membrane-bound organelles
- cytoplasm bound by the plasma membrane
Eukaryotic cells
- DNA nucleus bounded by a membranous nuclear envelope
- membrane-bound organelles
- cytoplasm in the region between the plasma membrane and the nucleus
In animals but not plant cells
lysosomes, centrosomes, and flagella (except for plant sperm)
In plant but not animal cells
chloroplast, central vacuole, cell wall, plasmodesmata
Mitochondrial DNA
contains 37 genes
12 provide instructions for making enzymes involved in oxidative phosphorylation
Nuclear lamina
made of intermediate filaments
has pores
Nucleus
DNA and proteins form chromatin (genetic material)
chromatin condense during mitosis to make chromosomes, located in the nuclear matric
Nucleolus
located within the nucleus
site of ribosomal and transfer RNA synthesis
Ribosomes
particles made of ribosomal RNA and protein
- free ribosomes - in the cytosol, make proteins that will function in the cytosol
- bound ribosomes - on the outside of the ER or nuclear envelope, make proteins that are exported or included in the cell’s membranes
Components of the endomembrane system
- nuclear envelope
- endoplasmic reticulum
- golgi apparatus
- lysosomes
- vacuoles
- plasma membrane
connected via transfer by vesicles
Endoplasmic reticulum
accounts for more than half the total membrane in many eukaryotic cells
continuous with the nuclear envelope
- smooth ER, lacks ribosomes
- rough ER, ribosomes studding surface
Smooth ER
synthesizes lipids including steroids
metabolizes carbohydrates (gluconeogenesis - glycogen into glucose)
detoxifies drugs and poisons (in liver)
stores calcium (trigger mm contraction)
Rough ER
bound ribosomes, secrete glycoproteins (important integral membrane proteins)
distribute transport vesicles
membrane factory for the cell
Lysosome
sac of hydrolytic enzymes, can digest macromolecules
Mitochondria
site of cellular respiration, ATP production
have double membrane
have proteins made by free ribosomes within the organelles themselves
contain their own DNA
smoother outer membrane and an inner membrane folded into cristae (intermembrane space and mitochondrial matrix)
some metabolic steps of cell respiration in matrix
cristae present large surface area for enzymes that synthesize ATP
Chloroplast
a plastid
thylakoids, membranous sacs, stacked to form a granum
stroma, internal fluid of a chloroplast
Microtubules
thickest of the 3
made of tubulin
- cell motility (cilia and flagella) (dynein)
- chromosome movements in cell division (centrosome, mitotic spindle)
- organelle movements
Microfilaments
Actin filaments (2 intertwined)
- changes cell shape
- mm contraction (myosin and actin)
- cytoplasmic streaming
- cell motility (ameboid) (also actin and myosin, pseudopodia)
- cell division (cleavage furrows during cytokinesis)
Intermediate filaments
fibrous proteins supercoiled into cables
made of keratin family subunit
- anchorage of nucleus and other organelles
- formation of nuclear lamina
Cell Wall
extracellular structure
made of cellulose embedded in other polysaccharides and protein
Extracellular Matric (ECM)
made of glycoproteins such as collagen, proteoglycans, and fibronectin
ECM proteins bind to receptor proteins in the plasma membrane called integrins (signaling from ECM to cytoskeleton)
Intercellular junctions
- Plasmodesmata
- Tight junctions
- Desmosomes
- Gap junctions
Plasmodesmata
plants only
channels that perforate cell walls
Tight junctions
prevent leakage of extracellular fluide
Desmosomes
Anchoring junctions
Gap junctions
cytoplasmic channels (hormone signaling)
Phospholipid Bilayer
Gorter & Grendel, 1925
Sandwich model
Davson and Danielli, 1935 sandwich
Fluid Mosaic
Singer and Nicolson, 1972
