Bio 103 Exam #1

nucleotide/nucleic acid

building blocks of DNA 

chromosome

DNA is storage; tightly wound around histone proteins

homologous chromosome

pairs of chromosomes (one from each parent) similar in size/shape/gene content - can differ in alleles (version of genes)

sister chromatid 

two identical copies of a single chromosome (DNA replication)

non-sister chromatid

comparison of chromatids from different parents and different homologous pairs

phosphate group (5C), deoxyribose sugar (3C), base (1C)

components of a nucleotide:

phosphodiester bond 

what bonds are nucleotides connected by?

replication

why is DNA antiparallel?

independent assortment, crossing over, random fertilization

genetic variation processes:

mitosis

duplication of sister chromatids → cytokinesis

meiosis

reproduction (diploid → haploid); how we pass along DNA to offspring without having too many chromosomes

ploidy

how many copies of DNA a cell has

zygote

a single diploid cell (undergoes mitosis to grow)

independent assortment

chromosomes can line up differently and split into different cells during meiosis 

crossing over

homologous pairs touch each other then exchange non-sister chromatids

random fertilization

equal likelihood of a sperm (2) getting with an egg (4)

alternation of generations

plants alternate between haploid and diploid during life cycle

alleles, diploid cells, dominate/recessive characteristics, law of segregation, law of independent assortment

mendels contributions:

genotype

combination of alleles

phenotype 

measurable characteristics 

gene

instructions

allele

version

law of segregation

during gamate formation, two alleles for a gene separate so that each gamete only receives one allele 

incomplete dominance 

heterozygote has intermediate phenotype (blend)

codominance 

allele effects coexist (polkadot) 

polygenic

multiple genes affect one trait

pleiotropic

one gene affects multiple traits

epistasis

effects of one gene alters another

9:3:3:1

dihybrid cross phenotype

get copies of your DNA into next generation

what is the meaning of life (biologically)?

fitness

an organisms ability to survive/reproduce in an environment; genetic representation in future generations

altruism

reduce own fitness to increase another’s

coefficient of relatedness

probability of having a shared allele

.5

r = siblings

.5 

r = offspring 

.25

r = niece/nephew

direct fitness

reproductive success of an individual

indirect fitness

reproductive success of an individual’s relatives

Kin Selection: to increase the chances that their genes will be passed onto future generations 

Why might individuals sacrifice their own interests to benefit their relatives?

indirect fitness

What kind of fitness does the kin selection theory deal with?

inclusive fitness

an individuals total genetic contribution to the next generation (direct and indirect)

haplodiploid

ploidy determines gender

transcription

DNA→mRNA

translation

mRNA→protein (amino acid)

gene expression

process where DNA directs the synthesis of proteins

mutations

source of new genes/alleles

point: silent mutation

a single nucleotide base is changed, resulting amino acid remains the same

point: missense mutation

a single nucleotide base is changed, resulting in a different amino acid being inserted into protein sequence 

point: nonsense mutation 

a single nucleotide base is changed, causes a premature stop of amino acid sequence (converts regular codon to a stop codon)

frameshift: insertion

one or more nucleotides are added to DNA sequence

frameshift: deletion

one or more nucleotides are removed from DNA sequence

DNA repair mechanisms (reversal enzymes, cut out sequence, fix sequence)

How do cells handle mutations?

CRISPR gene editing

“genetic scissors”/”find and replace”; precisely change DNA for medical/agricultural purposes