FINALS BIO FLASHCARDS

save my soul (cards 1-65: DNA, RNA, protein synthesis | cards 66-

DNA structure

complementary base pairing rule

covalent bonds everywhere except between 2 bases, which is hydrogen bond

double stranded, double helix

one strand in the 3’-5’ direction, one in the 5’-3’ direction

dioxyribose

large and less mobile than RNA

bases - ATCG

RNA structure

complementary base pairing rule (slightly different)

single stranded, single helix

synthesized in the 5’-3’ direction

bases - AUCG

ribose

smaller than DNA, more mobile

nucleic acids

purpose - stores genetic material

monomer - nucleotide

polymer - nucleic acids

sugars - dioxyribose (DNA) or ribose (RNA)

bases - acg and t (DNA) or u (RNA)

shape - helix

antiparallel

antiparallel

parallel, but running in opposite directions

DNA is antiparallel - one strand is in the 3’-5’ direction, one is in the 5’-3’ direction

gene

the information regarding how to produce a specific protein

nucleotide structure

3 parts - phosphate, sugar (dioxyribose or ribose), and base (ATCGU)

deoxyribose

the sugar found in DNA - missing an oxygen

ribose

the sugar found in RNA - has an additional oxygen compared to deoxyribose

Erwin Chargaff’s rules

discovered that the number of adenine (A) bases is equal to the number of thymine (T) bases in DNA and that the number of cytosine (C) bases is equal to the number of guanine (G) bases

Franklin and Wilkins

used x-ray crystallography to photograph a DNA molecule

Watson and Crick

Interpreted the DNA image taken by Franklin and Wilkins and used Chargaff’s rules to determine that the shape of DNA is a double helix

Components of DNA double helix

shaped like a ladder

rail of the ladder - sugar and phosphates

ring of ladder - 2 complementary bases

bonds in DNA

covalent bonds everywhere (shared electrons) with 2 hydrogen bonds between A and T and 3 hydrogen bonds between C and G

Direction of DNA

1 strand is in the 3’-5’ direction, the other is opposite, going in the 5’-3’ direction

antiparallel

complementary base pairing rule

in DNA: A bonds with T, C bonds with G

in RNA: A bonds with U, C bonds with G

2 categories of bases

purines and pyrimidines

purine

a molecule with 2 ring structures (A & G)

smaller word, bigger structure

pyrimidine

a molecule with 1 ring structure (C & T)

bases for DNA

ATCG

bases for RNA

AUCG

DNA replication

during the S phase of interphase, DNA replicates to ensure there is enough for the daughter cells

3 steps: unzip the DNA, complementary nucleotides bind, binding continues until strand is unzipped

step 1 - DNA replication

unzip the DNA

unzip the DNA - DNA replication

• replication occurs at different places on the DNA at the same time

• helicase unravels the helix to begin a new origin of replication

• as it unravels, supercoiling occurs downstream

  • topoisomerase prevents this

step 2 - DNA replication

complementary nucleotides bind

complementary nucleotides bind - DNA replication

• DNA polymerase adds nucleotides to each strand one at a time

  • can only work in the 3’-5’ direction

    • the leading strand (5’-3’) is fine because of this, it doesn’t stop, and there are no breaks in the addition of nucleotides

    • the lagging strand’s (3’-5’) nucleotides have to be added in chunks (called okazaki fragments)

• At the end, DNA ligase seals the gaps created from there being multiple origins of replication and the okazaki fragments

okazaki fragments

the fragments created because DNA polymerase can only add nucleotides from the 3’-5’ direction

found on the lagging strand

sealed together by DNA ligase

helicase

an enzyme that unravels the DNA during DNA replication

origin of replication

the space where helicase begins to unravel the DNA

there can be multiple on the same strand

topoisomerase

the enzyme that prevents supercoiling by cutting and resealing the DNA twist

DNA polymerase

adds new nucleotides to the DNA strand

can only work in the 3’-5’ direction

leading strand

the strand of DNA whose nucleotides are added continuously

always in the 5’-3’ direction

lagging strand

the strand of DNA whose nucleotides cannot be added continuously (due to the fact that DNA polymerase can only work in the 3’-5’ direction), so its nucleotides are added in chunks called okazaki fragments

always in the 3’-5’ direction

step 3 - DNA replication

complete

complete - DNA replication

semi-conservative replication

semi conservative replication

DNA replication with part of the molecule being recycled from a previous strand

• the parent strand serves as a template for new bases to be added onto to form a complementary strand

• each new DNA molecule is made up of a “new” strand and an “old” strand

DNA’s instructions

contains instructions to make proteins

ribosomes

location of DNA synthesis

located in cytoplasm

why is RNA used to make proteins

DNA is too large to leave the nucleus, so RNA is used as an intermediate to carry the instructions to make the proteins to the ribosomes

central dogma of genetics

DNA is used to make RNA, RNA is used to make proteins

transcription

production of RNA from DNA

3 parts - initiation, elongation, termination

location - nucleus

translation

production of proteins from RNA

location - ribosomes (cytoplasm)

3 parts - initiation, elongation, termination

initiation (TRANSCRIPTION)

an enzyme called RNA polymerase II (POL II) adds RNA nucleotides* one at a time

*(the same as DNA but uses U instead of T)

• transcription factors bind to the promoter region because they recognise an area of repeating T and A nucleotides (called the TATA box)

  • transcription factors encourage POL II to bind to that region

• when POL II binds, the DNA double helix unwinds

promoter region

the area that transcription bind to during initiation of transcription

elongation (TRANSCRIPTION)

POL II moves down the strand, unwinding the DNA

• as it unwinds, it adds complementary RNA nucleotides

• as it moves down, DNA reattaches further back

multiple POL II enzymes can attach to the same DNA molecule and work on synthesizing the same DNA strand

rate of transcription

60 nucleotides/second

termination (TRANSCRIPTION)

transcription continues until POL II reaches a segment of the DNA called the terminator, at which point the strand of mRNA is cut free

result - a strand of pre-mRNA that needs modification to be functional

modifications

• a 5’ cap is added to the 5’ end of the mRNA strand

  • the cap - a modified guanine nucleotide

  • function - to protect the strand and to be a location for the ribosome to attach to

• a tail is added to the 3’ end of the mRNA strand

  • tail = a series of 30-200 adenine nucleotides called a poly-a tail

  • protects the strand and helps with movement from the nucleus to the cytoplasm

RNA splicing

there are sections of DNA that do not code for anything in eukaryotes

these strands (introns) are removed by the spliceosome

leaves the exons which are combined to form a complete strand of RNA

introns

the sections of RNA that do not code for any protein

exons

the sections of RNA that code for protein

spliceosome

the protein that does the removing of the introns

protein review

monomer - amino acids

polymer - polypeptide (chain of amino acids held together by peptide bonds)

types of RNA

mRNA - messenger RNA - carries the code of DNA to ribosomes to make protein (made in nucleus, travels to cytoplasm)

rRNA - ribosomal RNA - combines with protein to form the ribosome

tRNA - transfer RNA - brings amino acids to the ribosome

translation summary

purpose - makes protein from the message carried in RNA and the message DNA holds

location - cytoplasm (ribosomes)

starts w - RNA

ends w - proteins

3 steps - initiation, elongation, termination

multiple ribosomes can attach to the same mRNA strand

transfer RNA

pairs of 3 nucleotides form a codon (located in mRNA)

tRNA brings amino acids - has the corresponding anticodon which binds to the codon and brings the amino acid to the ribosomes

genetic code

instructions for making the specific amino acids

4³ (64) possible codons

• some codons code for the same amino acids (21 possible amino acids)

ribosomal RNA (rRNA)

makes up most of a ribosome

constructed in 2 subunits called the large subunit and the small subunit

when the ribosome isn’t making protein, these 2 pieces are seperate in the cytoplasm

ribosome structure

3 locations

• A site: a new t-RNA comes and binds here, carrying an amino acid

• P site: has a tRNA with the growing amino acid chain

• E site: the tRNA exits, having lost its amino acid

initiation (TRANSLATION)

the mRNA and the 1st tRNA carrying the 1st amino acid bind to the small subunit of the ribosome, signaling for the large subunit to bind as well

• all of these pieces combined are called the initiation complex

• the ribosome starts translating when it reads AUG (the start codon which codes for methionine)

the mRNA is going to be pulled through the ribosome

elongation (TRANSLATION)

2 STEPS - codon recognition, peptide bond formation

codon recognition

a tRNA with the complementary anticodon (carrying an amino acid) comes into the A site and bonds with the mRNA

peptide bond formation

the ribosome pulls a section of the mRNA through. This brings the tRNA through so the tRNA that was in the P site is now in the E site and the tRNA in the A site is now in the P site. As this happens, the tRNA in the p—>G transition loses its amino acid, which binds to the tRNA in rhe a—>p transition

elongation (TRANSLATION)

when certain codons (stop codons) are reached, release factors will come and bind to the a site

• this signals the complex to separate into the 2 subunits, mRNA, tRNA, and the polypeptide

what is the mRNA and anticodons for the following DNA strand: TACGCTAGTACGATT

mRNA: AUGCGAUCAUGCUAA

anticodons: UACGCUAGUACGAUU

start codon

AUG

diploid

a cell with 2 sets of chromosomes (pairs of homologous chromosomes)

ex - somatic cell

haploid

a cell with one set of chromosomes (1 homologous, not a pair)

ex - gamete (sex) cell

number of chromosomes in humans

46

homologous chromosomes

code for the same trait, although they may code for them differently

1 passed onto offspring in each pair (random selection which one)

gene

a section of DNA which codes for 1 protein

always starts with TAC

humans have 2 versions of each gene

Gregor Mendel

Australian monk - part of an order that followed St. Augustine

being in the order gave him 2 things -

1. time

2. land

led to him experimenting with pea plants (see experiment flashcard)

FATHER OF GENETICS

animal reproduction

reproduce through the sperm fertilizing the egg

plant reproduction

use the pollen and the ovule

many can reproduce asexually (self pollination) because they can produce both gametes

Mendel wanted to see what traits offspring inherit from different parents

Mendel’s experiment

goal: to see how an organism gets a train when the parents have different options for that trait

he…

1. removed stamens from a plant and transferred pollen onto that plant’s pistil

   1. this ensured cross-pollination

2. used pea plants because they have a short generation time (6 months)

3. used purebread plants

4. used either-or traits

generation time

the time it takes to go from the parent generation to a sexually mature offspring

purebread

both alleles are either both dominant or both recessive (not heterozygous)

both homologous chromosomes have the same coding

either-or traits

traits with only 2 possibilities, which are clearly different

ex - detached vs attached earlobes

not an ex - height

alleles

an option of a trait on one homologous chromosome

homozygous

a pair of 2 alleles that code for the same trait the same way

ex - AA, aa

heterozygous

a pair of 2 alleles that code for the same trait differently

ex - Aa (capital letter must go first)

genotype

the genes that are inherited in the chromosomes - shown in allele notation

phenotype

the trait that is expressed in the organism

law of dominance

when 2 differnet alleles are inherited, the dominant trait is shown

dominant allele

the allele that is shown whenever inherited (shown either in heterozygotes - Aa or homozygous dominant - AA)

recessive allele

the allele that is shown in the phenotype only when paired with the same recessive allele (only shown when homozygous recessive - aa)

carrier

an organism that has but also does NOT express a trait

people heterozygous for a trait are carriers of their recessive trait

Allele notation

Capital letter- shows dominant trait, always written first when paired with a lowercase letter

lowercase letter - shows recessive trait

mating notation

P - parent generation

F₁ - offspring of parent gen

F₂ - offspring of first offspring gen (offspring of F₁ gen)

Laws of Meiosis

law of segregation, law of independent assortment

law of segregation

of an organisms 2 homologous chromosomes, it will only pass on 1 to its gamete cells (and thus to its offspring)

law of independent assortment

during metaphase 1, the side that the 2 homologous chromosomes line up on is random (meaning the chromosome that the parent passes onto its offspring is random)

punnett square

shows possible offspring and probability of a certain trait being passed onto an organism

test cross

performed to determine unknown genotype (if unknown, the phenotype = dominant trait)

STEPS:

1. cross the organism with another organism of the recessive genotype