science sol

key processes of the carbon cycle

photosynthesis, cellular respiration, decomposition, combustion, deforestation

carbon cycle

CO2 in air → photosynthesis → glucose in plant → eaten by consumer → cellular respiration → CO2 in air

nitrogen cycle

N2 in air → nitrogen fixation → nitrification → plant uptake → consumer eats plants → ammonification → denitrification → N2 in air

nitrogen fixation

bacteria convert N2 → NH3 (ammonia

nitrification

bacteria convert NH3 → NO2- →NO3- (nitrates usable by plants)

plant uptake (nitrogen cycle)

roots absorb NO3- and incorporate N into amino acids and proteins

ammonification

decomposers break down dead organisms and release NH3 back to the soil

denitrification

bacteria convert NO3- → N2 gas

what would happen if denitrifying bacteria were eliminated

NO3- would accumulate in soil leading to eutrophication

phosphorus cycle (6)

rocks/sediment with phosphorus → weathering/erosion → phosphate ions (PO4³-) enter soil/water → plants/fungi absorb PO4³-) → moves thru food chain → decomposers return to soil

phosphorus ions

PO4³-

7 steps of eutrophication

excess nutrients enter water → algae bloom → dies and accumulates → bacterial decomposition → hypoxia → dead zone

dead zones are worse in…

summer

why are dead zones worse in summer

more agricultural runoff, warm water holds less dissolved O2, thermal stratification, warm water = more bacteria

does warm or cold water hold less dissolved oxygen

warm

bioaccumulation

toxin builds up in one organism over its lifetime

biomagnification

toxin increases at each trophic level

Gause’s Law

competitive exclusion

competitive exclusion

2 species with identical niches cant coexist indefinitely

resource partitioning

similar species avoid competition

how does lichen lead to soil

secretes acids that chemically weather rocks and as they die organic matter accumulates which slowly builds proto soil

biological legacy in secondary succession

seeds, root fragments, fungal networks, soil

ocean acidification

CO2 dissolves in ocean → carbonic acid → lower pH → carbonate ions decrease → CaCO3 shells/skeletons of corals/oysters/mollusks dissolve and weaken

trophic cascade

top consumer removed triggers chain of negative effects

indirect species interactions leads to

indirect consequences

doubling time

time required for a population to double in size

photoperiod

daylight time

estuary

fresh and saltwater mix

trisomy

having 3 copies of a chromosome

nondisjunction

failure of chromosomes to separate during meiosis

nonsense mutation

substitution mutation that triggers a stop codon

silent mutation

substitution mutation that doesnt change the amino acid sequence

frameshift mutation

insertion/deletion that changes the reading frame

peptide bond

covalent bond between 2 amino acids in a polypeptide chain, formed by ribosome during translation

polypeptide

chain of amino acids produced during translation that folds into a functional protein

stop codon

signals end of translation - UAA, UAG, UGA

helicase

enzyme that unwinds/unzips DNA by breaking hydrogen bonds between the base pairs

DNA Polymerase III

enzyme that reads templete strand and adds complimentary nucleotides to build new DNA strand (5’→3’)

replication fork

y shaped region where DNA double helix is unwound and being copied

RNA

carries genetic info from DNA to ribosomes, one extra oxygen molecule, single stranded, uracil, ribonucleic acid

mRNA

messenger RNA, carries genetic code as codons from the nucleus to the ribosome

tRNA

transfer RNA, brings specific amino acids to the ribosome, has anticodon that matches the mRNA’s codon

rRNA

ribosomal RNA, structural component of the ribosome, helps form peptide bonds between amino acids

transcription

process of copying DNA into mRNA, performed in the cytoplasm by RNA polymerase

RNA polymerase

enzyme that unwinds DNA and synthesizes an mRNA strand during transcription

template strand

strand of DNA read 3’→5’ by RNA polymerase, produces complimentary mRNA, also called antisense

coding strand

non template strand of DNA identical to mRNA produced (except T→U), also called sense strand

promoter

DNA sequence that signals where RNA polymerase should bind to begin transcription

intron

non coding sequence in a pre mRNA that is removed before the mRNA leaves the nucleus

exon

coding sequence in a pre mRNA that is retained and joined together to form the mRNA

translation

process of using the mRNA sequence to assemble a polypeptide at the ribosome

codon

3 nucleotide sequence on mRNA that codes for amino acid

anticodon

on tRNA, complimentary to and base pairs with codon

start codon

AUG

nucleotide

monomer of nucleic acid

deoxyribose

5 carbon sugar in DNA

what part of a nucleotide encodes genetic info

the nitrogenous base

hydrogen bond rules: AT ? GC ?

AT2 GC3

what bond holds together nitrogenous bases

hydrogen

hydrogen bond, weak or strong and why

weak bond allows for easy separation

why is DNA replication semi conservative

one og strand and one newly synthesized strand

what process is DNA → mRNA

transcription

what process is mRNA → protein

translation

where is transcription

nucleus

where is translation

cytoplasm at ribosomes

key enzyme in transcription

RNA polymerase

key thingie in translation

ribosome

whats ribosomes made of

rRNA and proteins

whats made during transcription

mRNA

whats made during translation

polypeptide chain

starting material in transcription

DNA template strand

starting material in translation

mRNA strand

base pairing during transcription

A-U T-A G-C C-G

what pairs together during translation

NOT TALKING ABT THE NITROGENOUS BASES

mRNA codon ←> tRNA anticodon

signal to start transcription

promoter sequence on DNA

signal to start translation

AUG on mRNA

signal to stop transcription

terminator sequence on DNA

signal to stop translation

stop codon on mRNA

central dogma

big picture - flow of genetic info

flow of genetic information

DNA (nucleus) → replication → transcription → translation → protein

what kind of mutation is sickle cell and where

substitution in hemoglobin

downs syndrome

trisomy 21, extra copy of chromosome 21

deletion - chromosomal mutation

segment of chromosome is lost

duplication - chromosomal mutation

segment of chromosome is copied and repeated

inversion - chromosomal mutation

segment is removed and reinserted in reverse orientation

translocation - chromosomal mutation

segment is moved to non homologous chromosome

steps of translation and transcription

initiation → elongation → termination

steps of translation - initiation

ribosome assembles around mRNA, ribosomal subunit binds to 5’ of mRNA until it finds the start codon an the first tRNA binds to AUG

steps of translation - elongation

ribosome reads mRNA codons 3 bases at a time, for each codon: (1) a tRNA with matching anticodon carries amino acid to the ribosome (2) peptide bond forms between new amino acid and growing polypeptide chain (3) ribosome moves one codon forward and repeats until stop codon

steps of translation - termination

ribosome reaches stop codon, no tRNA matches and a release factor protein enters the site and causes the ribosome to disassemble, the completed polypeptide is released and becomes functional

peptide bond

the covalent bond that links 2 amino acids together in the polypeptide chain

steps of transcription - initiation

RNA polymerase binds to promoter sequence, double helix unwinds

steps of transcription - elongation

RNA polymerase moves along antisense and reads bases from 3’→5’, assembling a complimentary mRNA strand from 5’→3’

steps of transcription - termination

RNA polymerase reaches terminator sequence, releasing the mRNA and the double helix reforms

first step of DNA replication

helicase unwinds the double helix and breaks hydrogen bonds between base pairs, separating the strands at the replication fork

second step of DNA replication

each separated DNA strand serves as template for building a new complimentary strand

third step of DNA replication

DNA polymerase III moves along each template strand and adds free complimentary nucleotides from 5’→3’

fourth and final step of DNA replication

2 complete double stranded DNA molecules are formed

stability of DNA

very - designed for long term storage

stability of RNA

not very - temporary and degrades after use