BIo

genotype

genotype

An organism's genetic makeup, or allele combinations.

phenotype

An organism's physical appearance, or visible traits.

Homozygous

An organism that has two identical alleles for a trait (BB or bb)

Heterozygous

An organism that has two different alleles for a trait (Bb or GF)

Recessive

An allele that is masked when a dominant allele is present

Dominant

Describes a trait that covers over, or dominates, another form of that trait.

Codominance

A condition in which BOTH alleles for a gene are fully expressed (ex: blood types; speckled black and white chickens)

Incomplete Dominance

Situation in which one allele is not completely dominant over another allele (ex: snap dragons -- blend/mix of traits)

sex-linked traits

Traits controlled by genes located on sex chromosomes; Y chromosome does not carry an allele for the trait (ex: hemaphelia; color-blindness)

Pedigree

A chart or "family tree" that tracks which members of a family have a particular trait

How do you know if the pedigree is recessive?

In a recessive pedigree it is possible for the children to have the expressed trait while neither parent have it. This means both parents are carriers (heterozygous) and the trait is recessive.

Helicase

An enzyme that unzips the double helix of DNA at the replication forks during DNA replication

When does DNA replicate?

During S-Phase of Interphase

DNA polymerase

Enzyme involved in DNA replication that joins individual nucleotides to produce a DNA molecule ("the DNA builder")

RNA polymerase

Enzyme similar to DNA polymerase that binds to DNA and separates the DNA strands during transcription; it then joins individual nucleotides to produce the new RNA molecule ("the RNA builder")

semi-conservative replication

Each half of an original DNA molecule serves as a template for a new strand, and the two new DNA molecules each have one old and one new strand.

recombinant DNA

DNA produced by combining DNA from different sources (ex. insulin gene from humans combined with DNA of bacteria)

Transcription

process of making an mRNA molecule from a DNA template; Step 1 of protein synthesis

Translation

Process by which mRNA is decoded (translated) and a protein is produced; Step 2 of protein synthesis

Location of transcription

nucleus

location of translation

ribosome in the cytoplasm or rough ER

other names for protein synthesis

gene expression; central dogma

Codon

three-nucleotide sequence on mRNA that codes for a single amino acid

Anti-codon

group of three bases on a tRNA molecule that are complementary to an mRNA codon

tRNA

transfer RNA; type of RNA that carries amino acids to the ribosome

mRNA

messenger RNA; type of RNA that carries instructions from DNA in the nucleus to the ribosome

rRNA

ribosomal RNA; type of RNA that makes up part of the ribosome

Gene mutation

a change in the DNA sequence of a gene

Substitution

A mutation in which a nucleotide in DNA is replaced with a different nucleotide

deletion mutation

a mutation in which a nucleotide is removed from a DNA sequence on a gene; causes a frameshift

insertion mutation

a mutation in which a nucleotide is added to a DNA sequence on a gene; causes a frameshift

Frameshift

mutation that shifts the "reading" frame of the genetic message by inserting or deleting a nucleotide

Evolution

change in the gene pool of a population over time

natural selection

A mechanism of evolution in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits.

Fitness

how well an organism can survive and reproduce in its environment

Lamark

before Darwin; inheritance of acquired characteristics; thoughts traits were passed on based on use/disuse; he was WRONG

Darwin

natural selection and descent with modification

Microevolution

evolutionary change within a species or small group of organisms, especially over a short period.

Macroevolution

large-scale evolutionary changes that take place over long periods of time; study of common ancestry and the tree of life

divergent evolution

when two or more species sharing a common ancestor become different over time (diverge); homologous structures

convergent evolution

when two or more species share common characteristics but are unrelated and do not have common ancestor for that trait; analogous structures

homologous structures

same structure but different function (arm bones); common ancestry for the trait; divergent evolution

analogous structures

different structure but same function (wings); no common ancestry for the trait; convergent evolution

Coevolution

Process by which two species evolve in response to changes in each other (bee & flower)

punctuated equilibrium

Pattern of evolution in which long stable periods are interrupted by brief periods of more rapid change

Embryological Evidence

Looking at the embryo in early stages of development: 1st stages all look similar which indicates a common ancestor

Biochemical Evidence

using DNA or amino acid sequences of species to determine relatedness

vestigial structures

A structure that is present in an organism but no longer serves its original purpose; gives clues about evolutionary past; ex: whale with a hip bone

Mendle

Father of genetics

Law of Segregation

two alleles will separate during gamete formation in meiosis

Law of Dominance

a dominant allele will express itself over a recessive allele

Law of Independent Assortment

the inheritance of one trait has no effect on the inheritance of another

monohybrid cross

a cross in which only one characteristic is tracked

dihybrid cross

a cross in which the inheritance of two characteristics are tracked

blood typing genotypes

AA/AO or BB/BO or AB or OO

multiple alleles

three or more forms of a gene that code for a single trait (ex: blood typing -- A/B/O alleles)

3 characteristics of DNA

deoxyribose sugar; double stranded; A/T & C/G

3 characteristics of RNA

ribose sugar; single stranded; A/U & C/G

transgenic organism

made when genes from one type of organism are inserted into the genome of a different organism

GMO (genetically modified organism)

organisms that either have genes added OR have genes deleted.

gene therapy

involves either replacing mutated genes or inactivating them completely

genetic screening

analyzes the genome of a person or an unborn baby to detect certain disorders

Cloning

Making a genetically identical copy of DNA or of an organism.

designer babies

babies whose genetic characteristics are artificially created