exam 1 molec cell chapters 2, 3,4,14

Gregor Mendel’s assumption that allowed him to predict patterns of inheritance

each trait is determined by a pair of inherited factors (genes)

allele

one copy gene inherited by each parent

genotype

genetic makeup

phenotype

physical appearance

diploid

contains 2 copies of each chromosome

haploid

contains 1 copy of each chromosome

genes on different chromosomes are inherited:

independent of one another (segregated)

genes on the same chromosome are inherited:

together (linked)

DNA structure

double helix

semiconservative replication

one strand of parental DNA is conserved in each progeny DNA molecule

(broad) function of DNA polymerase

forms a new DNA strand by adding nucleotides to the existing DNA template strand

number of strands in RNA

one single strand

RNA sugar

ribose

base replaced by uracil in RNA

thymine

transcription

RNA synthesis from DNA template

translation

protein synthesis from RNA template

(broad) function of RNA polymerase

synthesis of messenger RNA (mRNA) from a DNA template

function of ribosomal RNA (rRNA)

site of protein synthesis

function of transfer RNA (tRNA)

align amino acids along the mRNA template

retroviruses

group of viruses that synthesis DNA from RNA in infected cells

reverse transcriptase

experimental; generates DNA from an RNA template

restriction endonuclease

cleaves DNA at specific sequences

plasmid function

cloning DNA inserts of up to a few thousand base pairs

plasmid origin of replication (ori)

DNA sequence that signals host DNA polymerase to start replication

gene transfer

introducing cloned DNA into plant and animal cells (for studying gene function)

transfection

method of gene transfer using infectious viral DNA

gene

DNA segment that is expressed to yield a functional product

exon

coding sequence in genes

intron

noncoding sequence in genes

RNA contains (exons, introns, both):

both exons and introns

mRNA contains (exons, introns, both):

exons only

histone

gene that lacks introns

intron frequency increases with:

genome size and complexity

functional products encoded by introns

proteins and noncoding RNAs

alternative splicing

different proteins are encoded from the same gene by joining exons in different combinations

simple-sequence repeats

tandem arrays of short sequences (1 - 500) of nucleotides

quaternary structure

interactions between different polypeptide chains in proteins composed of more than one polypeptide

number of polypeptide chains in hemoglobin

four polypeptide chains

gene family

members of a group of related genes

2 ways gene families are transcribed

in different tissues

at different stages of development

prokaryotic DNA

single chromosomes, circular DNA

eukaryotic DNA

multiple chromosomes, linear DNA

chromatin

a complex of DNA and proteins

major proteins in chromatin

histones

H1

type of histone

H2A

type of histone

H2B

type of histone

H3

type of histone

H4

type of histone

nucleosome

basic structural unit of chromatin

nucleosome core particles

147 base pairs of DNA wrapped 1.67 turns around a histone core (sealed by, but doesn’t include H1)

chromatosome

H1 bound to DNA where it enters the core particle

number of histone molecules in one nucleosome core particle

8 (2 of each histone, not including H1)

total condensation of DNA with histones

fiftyfold

euchromatin during interphase

loosely condensed, distributed throughout the nucleus

heterochromatin during interphase

highly condensed, ~10% of all chromatin

heterochromatin functionality

transcriptionally inactive, highly repeated DNA sequences

centromere

DNA sequences to which proteins bind, forming a kinetochore

spindle microtubules bind to:

the kinetochore

telomere

sequence at the end of a chromosome, required for replication of linear DNA molecules

telomere structure

repeated sequences that forms a loop structure and ends with a 3’ overhang of single-stranded DNA

telomere function

stabilizes DNA and resists degradation; determines lifespan/reproductive capacity of cells

telomerase

synthesizes telomeres via reverse transcriptase

organic molecules

carbohydrates, lipids, proteins, nucleic acids

most abundant molecule in cells

water

polarity of water

polar

hydrogen bonds

bond that forms between polar organic molecules

polar molecule interactions with water

hydrophilic

nonpolar molecule interactions with water

hydrophobic

ΔG < 0

reaction proceeds in forward direction, builds energy

ΔG > 0

reaction proceeds in reverse, consumes energy

location where energy is stored in ATP

bonds between the phosphates

result of ATP hydrolysis

large decrease in free energy

ATP synthesis

coupled to energy-yielding reactions

ATP hydrolysis

coupled to energy-requiring reactions

molecule that provides the principle source of cellular energy

glucose

structure of glucose

ring formed by 6 carbon sugar

polymers of a few sugars

oligosaccharides

polymers of 100s or 1000s of sugars

polysaccharides

polysaccharide bond

α (1→4) glycosidic bond

glycogen

storage of glucose in animal cells

starch

storage of glucose in plant cells

molecules that contain α (1→6) glycosidic bonds

glycogen, amylopectin

cellulose

main structural component of plant cell walls; glucose in ß configuration

roles of lipids

energy storage, major component of cell membranes, cell signaling

fatty acids

long hydrophobic hydrocarbon chains (16 or 18 carbons) with a carboxyl group (COO^-) at one end

unsaturated fatty acids

one or more double bonds

saturated fatty acids

no double bonds, only nonpolar C-H bonds

triacylglycerols (fats)

3 fatty acids linked to a glycerol molecule; insoluble in water

phospholipid

2 fatty acids (hydrophilic tails) joined to a phosphate group with a polar attachment (hydrophilic head); amphipathic

glycerol phospholipids

2 fatty acids bound to 2 carbons in glycerol

sphingomyelin

the only nonglycerol phospholipid in cell membranes

glycolipids

2 hydrocarbon chains and a carbohydrate polar head group (amphipathic)

cholesterol

4 hydrophobic hydrocarbon rings and a polar hydroxyl (OH) group (amphipathic)

derivatives of cholesterol

steroid hormones

function of steroid hormones

act as chemical messengers

structure of steroid hormones

contain 4 hydrocarbon rings

purines

adenine and guanine

pyrimidines

cytosine, thymine, uracil