Unit 2 Genetics vocabulary

Principle of segregation

each diploid organism possesses 2 alleles at a locus that separate in meiosis and that one alle passes into each gamete

principle of independent assortment

each homologous pair sorts independently of each other

Recombination

sorting of alleles into new combos

Linked genes

genes located close together on same c'some

crossing over

breaks up genes that are close together on same c'some

nonrecombinant/parental gametes

contain only original combo of alleles that were in parents

recombinant gametes

have new combo of alleles

incompletely linked genes

genes that gave crossing over

recombination frequency/rate of recombination

# of recombinant progeny/total number of progeny

(shows how often alleles in gametes appear in new combos)

coupling/cis configuration

wild type alleles are on one c'some and mutant are on the other c'some

repulsion/ trans configuration

each c'some contains 1 wild type and 1 mutant allele

metacentric

centromere is located in middle (arms equal)

submetacentric

centromere is toward one end ( one long or short arm)

acrocentric

centromere is near one end making long arm and knob (very short ) arm

telocentric

centromere is at very end of chromosome

karyotype

complete set of c'somes, goes in descending order of size

chromosome duplication

part of c'some has been doubled

types of chromosome duplications

• Tandem: duplicated segment is immediately next to OG segment

• Displaced: located some distance from OG segment

• Reverse: duplicated is inverted/backwards (duplicate is first)

segmental duplication

duplications that are 1,000+ base pairs

types of segmental duplication

• Intrachromosomal: found on same c'some

• Intrachromosomal: found on different c'some

unequal crossing over

c'somes misalign during cross over events, causes duplications and deletions

Inversion

flips a c’some segment

types of inversion

• Paracentric (does not include centromere)

• Pericentric (includes centromere)

translocations

move DNA between nonhomologous chromosomes

translocation types

• Nonreciprocal: one-way transfer

• Reciprocal: two-way exchange

aneuploidy

change in # of individual c’somes

types of aneuploidy

Nullisomy: loss of both members of a homologous pair

Monosomy: loss of one member of a homologous pair

Trisomy: gain of 1 chromosome, resulting in 3 homologous chromosomes

Tetrasomy: gain of 2 homologous chromosomes, resulting in 4 homologous chromosomes

polyploidy

addition of entire chromosome sets

polyploidy types

auto-polyploidy: extra chromosome sets are derived from the same species

allopolyploidy: extra chromosome sets are derived from 2+ species

nucleotides

linked repeating units, contains a sugar, phosphate, and a base

chargaff’s rule

amount of A=T, amount of G=C

transforming principle

DNA, substance responsible for transformation

primary structure

nucleotide structure and how nucleotides are joined together

Sugar group

pentose

•  

  • RNA sugar: ribose has hydroxyl group attached to 2 Carbon

    • Additional O makes it reactive/less stable

  • DNA sugar: Deoxyribose has H attached to 2 Carbon

  • 
    

Nitrogenous base

Purine: 6-member ring attached to a 5-member ring (A & G)

Pyrimidine: 6-member ring only (T&C&U)

phosphate group

P atom bonded to 4 O atoms, carries negative charge

secondary structure

DNA's stable 3 dimensional configuration (helix structure)

tertiary structure

complex packing arrangements of double-stranded DNA in chromosomes

supercoiling

DNA helix is strained by being overwound or underwound, can't be compensated by turning ends of double helix

supercoiling types

• Positive: over rotated, energy is used to add or remove turns, strain is placed and twists on its self

• Negative: underrotated molecules, mostly found

  • Makes strands easier to separate

  • Can be packed into a smaller space

topoisomerase

 enzymes that add or remove rotations from DNA by breaking nucleotides temporarily, rotating ends, then rejoined ends

chromatin

DNA and proteins

types of chromatins

• Euchromatin:  normal process of condensation and decondensation in cycle

  • Majority of chromosomal material

  • Transcription takes place

• Heterochromatin: remains highly condensed throughout cell cycle

  • All c'somes have this at centromeres and telomeres

  • Y c'some

  • May occur during developmental stages

    • Along X when it becomes deactivated

  • No transcription, no crossing over

  • Replication late in S phase

nucleosome

core particle consisting of DNA wrapped 2 times around an octamer of 8 histone proteins ( 2 of each: H2A, H2B, H3, H4)

telomeric sequences

 consist of repeated units of series of AT followed by several G sequences

Denaturation

process where hydrogen bonds are heated enough to separate 2 strands complete

Renaturation

cooling of hydrogen bonds where single strands collide

hybridization

 2 single strands from different sources will anneal/recombine if they are complementary

unique-sequence DNA

consist of sequences that present only a 1 or few times in genome

Gene family

DNA present in several similar but not identical copies

Repetitive DNA

exists in many copies, moderate and highly repetitive

moderately repetitive DNA

• Tandem repeats: appear one after another, clustered on particular locations

• Interested repeats: scattered throughout genome

  • Short interspersed elements (SINEs): short repeats

  • Long interspersed elements (LINEs):  several thousand bp making up repeats

the endosymbiotic theory

 proposes that mitochondria and chloroplasts were free-living bacteria that became internal inhabitants of early eukaryotic cells, and endosymbiont genes were lost or transferred to the nucleus