Chapter 2 Molecules and Cells Flashcards
What can not be broken down into smaller substances?
elements
What is the smallest unit of an element?
an atom
What are atoms made of?
protons, neurons, and electrons
What are ionic bonds?
bonds between oppositely charged atoms
How are ions formed?
when atoms lose or gain an electron
What bonds are easily dissolved by water?
ionic bonds
What is entropy?
energy put into a system can favor certain reactions that build complexity
What are covalent bonds?
a strong bond that results from the sharing of an electron pair between two atoms
What element forms covalent bonds?
carbon!
What is a nonpolar covalent bond?
equal sharing of electrons
What is a polar covalent bond?
unequal sharing of electrons
What makes up 75% of a cells weight?
water
Is water polar or non polar?
polar
What does the polar nature of water lead to?
hydrogen bonds
What are hydrogen bonds?
not very strong, but they are numerous and lead to the sticky nature/life-allowing properties
What are the properties of water?
heat absorption, sticky, solid (ice) is less dense than liquid, almost universal solvent (cannot dissolve lipids)
What can water not dissolve?
lipids
What is pH?
measure of the concentration of hydrogen ions
What is a basic pH?
pH greater than 7
What pH has a low concentration of hydrogen ions?
basic pH
What pH has a high concentration of hydrogen ions?
acidic pH
What is an acidic pH?
pH less than 7
Why are both acids and bases damaging?
because they are highly reactive with other substances
What is a neutral solution pH?
pH of 7
What does the human body maintain a blood pH of?
7.4
What do acids do?
release more H+
What do bases do?
accept H+
What do buffers do?
release OH- and accept H+
What are carbohydrates?
CH2OH
What is anabolism?
building larger molecules from subunits
What is catabolism?
breaking down larger molecules into subunits
What does dehydration synthesis (condensation) do?
reactions form glycosidic bonds
What do hydrolysis reactions do?
break glycosidic bonds (splitting water)
What are lipids?
carbon chains that have lots of hydrogens attached to them
What is a triglyceride?
1 glycerol and 3 fatty acids
What is a saturated lipid?
no double bonds
What is an unsaturated lipid?
has double bonds
What are phospholipids?
polar, hydrophilic phosphate head and 2 nonpolar, hydrophobic fatty acid tails
What are phospholipids good for?
forming membranes!
What lipids are amphipathic?
phospholipids
What are steroids?
a type of lipid where the carbon atoms are formed into rings
What is the most important form of steroids in the body?
cholesterol because its the base for forming hormones
What lipid is very hydrophobic?
steroids
What is cholesterol used for?
giving structure to cell membrane, used to synthesize testosterone, estrogen, and cortisol
What are proteins?
the building blocks of life
What reaction forms a peptide bond?
dehydration reaction
What is the R group?
the functional group
What are nonpolar amino acids?
they are hydrophobic and avoid contact with liquids
What are polar amino acids?
have “R” groups that are hydrophilic and seek contact with aqueous solutions
What are secondary structions?
pleated sheets and helixes
What is an example of quaternary structure?
hemoglobin
What bonding established secondary structure?
intramolecular bonding
What are the nucleic acid bases?
guanine, thymine, cytosine, adenine
What do A’s base pair with?
T
What do G’s base pair with?
C
What is DNA made of?
deoxyribonucleotides
What is RNA made of?
ribonucleotides
What does DNA contain?
thymine
What does RNA contain?
uracil
What does DNA do?
stores genetic information
What does RNA do?
carries the information, does NOT store it
What is the cell theory?
- All living things are made of cells (at least 1)
- Every new cell comes from the division of a preexisting one
What does the plasma membrane contain?
phospholipids, cholesterol, proteins (integral, peripheral)
What is the fluid-mosaic model?
proteins and lipids that are in constant motion
What is glycocalyx?
a layer of macromolecules surrounding the plasma membrane
What does the plasma membrane do?
gives form to cell and controls passage of material into and out of cell
What are vesicles?
pinched inclusion of membranes that contain molecules or organelles
What is phagocytosis?
“cellular eating” performed by immune cells (white blood cells)
What is endocytosis?
membrane furrows inward
What is pinocytosis?
for of endocytosis - “cellular drinking” non specific
What is receptor-mediated endocytosis?
requires specific receptors
What is exocytosis?
secretory products are contained within a membrane-enclosed vesicle that fuses with the plasma membrane so that the lumen of the vesicle is open to the extracellular environment
What are cilia?
tiny projections that make a “current” to move substances
What are microvilli?
tiny projections found in the kidneys and intestines to promote absorption
What are flagellum?
large, whiplike extensions used for motility (sperm)
What is the function of microvilli?
to give larger SA for organs, not used to move
What does the cytoplasm contain?
the cytoskeleton
What is the cytoplasm?
fluid, jellylike substance between the plasma membrane and the nucleus in which organelles are suspended
Where are organelles anchored?
in the cytoplasm
What is the endoplasmic reticulum?
system of interconnected membrane-forming canals and tubules
What does the smooth endoplasmic reticulum do?
metabolizes nonpolar compounds and stores calcium in striated muscle cells
What does rough endoplasmic reticulum do?
assists in protein synthesis
What are ribosomes?
granular particles composed of protein and RNA
What do ribosomes do?
synthesize proteins
What is the golgi complex?
cluster of flattened membranous sacs
What do the golgi complex do?
synthesizes carbohydrates and packages molecules from the endoplasmic reticulum for secretions; secretes lipids and glycoproteins
What is the mitochondria?
membranous sacs with folded inner partitions
What does the mitochondria do?
releases energy from food molecules and transforms energy into usable ATP
What are lysosomes?
membranous sacs
What do lysosomes do?
digest foreign molecules and worn/damaged organelles
What are peroxisomes?
spherical membranous vesicles
What do peroxisomes do?
contain enzymes that detoxify harmful molecules and break down hydrogen peroxide/oxidizing agents
What are centrosomes?
non-membranous mass of 2 rodlike centrioles
What do centrosomes do?
help to organize spindle fibers and distribute chromosomes during mitosis
What are vacuoles?
membranous sacs
What do vacuoles do?
store and release various substances within the cytoplasm
What are microfilaments/microtubules?
thin, hollow tubes
What do microtubules and microfilaments do?
support cytoplasm and transport materials within the cytoplasm
What is the nuclear envelope?
double-layered membrane that surrounds the nucleus
What is the nuclear envelope composed of?
protein and lipid molecules
What does the nuclear envelope do?
supports nucleus and controls passage of materials between nucleus and cytoplasm
What is the nucleolus?
dense nonmembranous mass composed of proteins and RNA molecules
What does the nucleolus do?
produces RNA for ribosomes
What is chromatin?
fibrous strands composed of protein and DNA
What does chromatin do?
contains genetic code that determines which proteins (including enzymes) will be manufactured by the cell
What does the smooth ER make?
lipids
What are free ribosomes?
make proteins destined for inside the cell
What are bound ribosomes?
make proteins destined for outside the cell
What is the rough ER made of?
studded with ribosomes
What does the smooth ER make?
steroids and store calcium in muscle cells
Why are transmembrane proteins important?
they are the premier way that a cell interacts with its environment
What does a channel protein do?
permits simple diffusion of solutes in aqueous solution or osmosis of water through a membrane
What does a transporter (carrier) protein do?
binds noncovalently and reversibly with specific molecules or ions to move them across a membrane intact, actively transport through membrane if using metabolic energy and use facilitated diffusion if metabolic energy is not used
What does an enzyme protein do?
catalyzes a chemical reaction where covalent bonds are made or broken
What does a receptor protein do?
binds noncovalently with specific molecules and initiated a change in membrane permeability or cell metabolism; mediate responses of a cell to chemical signals arriving at the outside of the cell membrane
What do structural proteins do?
attaches to other molecules to anchor intracellular elements to the cell membrane, creates junctions between cells or establishes structural relations
What is lumen?
the open central cavity on the inside
What are tight junctions?
when cell membranes are touching, doesn’t allow much do go between the cells
What are desmosomes?
strong connection between two cells that fuse together the cytoskeletons of the two cells
What are gap junctions?
protein channels allow material to move freely between the two cells
What is the paracellular path across epithelium?
between cells
What is the transcellular path across epithelium?
through and across cells
What is hyperbolic kinetics?
the reaction velocity increases asymptotically approaching a maximum velocity, Vmax
What is sigmoid kinetics?
the approach to Vmax follows an S-shaped (sigmoid) trajectory
What is an uncatalyzed reaction?
the activation energy - the increased energy required to achieve transition state - is greater without catalysis
What is a catalyzed reaction?
the activation energy - the increased energy required to achieve transition state - is greater with catalysis
