Nucleic Acids, Meiosis, Mitosis

nucleic acid

genetic material of the cell & composed of recurring monomers

nucleotides

recurring monomers that form nucleic acids

components of nucleic acids

pentose sugar, phosphate group attached to 5’C atom, nitrogenous base attached to 1’C atom

condensation reaction forming nucleotides

phosphate group links to the sugar of another at the 3’-hydroxyl position

covalent phosphodiester bond

bond between nucleotides

double ringed purine bases

guanine and adennine

single ringed pyrimidine bases

cytosine, thymine (DNA), uracil (RNA)

bond between nitrogen bases

hydrogen bond creating complementary sequence

complementary nitrogen bases

guanine and cytosine, adenine and thymine/uracil

DNA

master template for all genetic instructions, passes hereditary info

DNA components

thymine, deoxyribose, double stranded

DNA base rule

antiparallel, forming a ladder structure so bases face each other

RNA

functions to transfer genetic info for coding; involved in protein synthesis

RNA Components

uracil, ribose, single stranded

RNA production

from DNA template via condensation of nucleotide monomers

3 types of RNA

Messenger RNA, Transfer RNA, Ribosomal RNA

phases of mitosis

prophase, metaphase, anaphase, telophase

phases of a cell cycle

cell growth (G1), DNA replication (S), Prep for mitosis (G2), mitosis/meiosis

chromosome

dna with histone protein

somatic cells

all diploid, all cells except gametes, undergoes mitosis

gametes

all haploid, undergoes meiosis

cytokinesis

physical separation of the cytoplasmic components into 2 daughter cells

prophase

chromosomes condense and become visible, spindle fibers emerge from centrosomes, nuclear envelop breaks down

metaphase

miotic spindle is developed, chromosomes line up at equator

anaphase

cohesion protein breaks down, sister chromatids are pulled apart toward poles

telophase

chromosomes arrive at opposite poles and decondense

meiosis

used for sexual reproduction and genetic variation, 2n → n

mitosis

used for growth, repair, and asexual reproduction, 2n → 2n

chromosome non-disjunction

failure of chromosomes to separate during anaphase

non-disjunction trisomy 21 result

down syndrome

non-disjunction XXY result

klinefelter syndrome

non-disjunction X result

turner’s syndrome

how does meiosis generate diversity

crossing over and random orientation of bivalents

crossing over in meiosis

takes place during prophase 1, arms of a chromatid can swap at random (at this chiasmata)

random orientation of bivalents

random separation of chromosome pairs to each pole, 50% chance