Genetics and Molecular Biology Flashcards
Movement of a chromosome piece to another chromosome location
Transposition
Genes or small DNA fragments that can move to a new location
Transposable elements (jumping genes)
She discovered transposition in 1950s
Barbara McClintock
Discovery of DNA structure in 1953 by
James Watson and Francis Crick
Chromosomes composed two types of large molecules:
DNA and protein
DNA molecule organized into chain of nucleotides composed of three parts:
• Nitrogenous base
• 5-carbon sugar (deoxyribose)
• Phosphate group
Hydrogen bonds hold base on one side of helix to another base on other side
rungs of ladder
Segment of DNA that directs protein synthesis
Gene
Sum total of DNA in an organism’s chromosomes
Genome
New DNA molecule consists of one strand from original molecule and another built using that parental strand as a template
semi-conservative replication
Copy of gene message made from DNA template using RNA building blocks
Transcription
Contains ribose, instead of deoxyribose sugars; single stranded; thymine replaced by uracil
RNA
RNA translated to produce proteins. Occurs in cytoplasm
Translation
Translated to produce proteins
Messenger RNA (mRNA)
Machinery for translation
Transfer RNA (tRNA)
Machinery for translation
Ribosomal RNA (rRNA)
sequence at end signals transcription enzymes to fall off
Terminator DNA
fundamental to control of gene expression
Nonprotein-coding DNA
Sequence of three amino acids that recognize and pair with codon on mRNA
Anticodon
Agents that alter DNA sequences
Mutagens
Occurs in body cell
Somatic mutation
Occurs in tissues that will produce sex cells
Germ-line mutation
Study of chromosome behavior and structure from a genetic point of view
Cytogenetics
Chromosomal piece breaks and reinserts in opposite orientation
Inversion
Chromosomal piece breaks off and attaches to another chromosome
Translocation
Carries one or more extra chromosome(s), or is missing one or more chromosome(s)
Aneuploid
Has at least one complete extra set of chromosomes
Polyploid
Offspring of parental generation
First filial generation (F1)
Offspring of F1 plants
Second filial generation (F2)
Factors (alleles), which always occur in pairs, control the inheritance of various characteristics
Law of unit characters
For any given pair of alleles, one (dominant) may mask the expression of the other (recessive)
Law of dominance
Organism’s physical appearance
Phenotype
Genetic information responsible for contributing to phenotype
Genotype
Start with cross between two true-breeding parents differing for a trait
Monohybrid Cross
F1 plants intercrossed to produce F2 generation
Monohybrid Cross
Start with parents differing in two traits
Dihybrid cross
Factors (genes) controlling two or more traits segregate independently of each other
Law of independent assortment
Genes on same chromosome
Linked genes
Genes on different chromosomes
Unlinked genes
A cross between a hybrid and one of its parents. If we have desireable trait to preserve
Backcross
Cross between a plant having a dominant phenotype with a homozygous recessive plant. This will determine whether plant with dominant phenotype is homozygous or heterozygous
Testcross
Heterozygote is intermediate in phenotype to the two homozygotes
Incomplete dominance
(absence of dominance)
exhibit range of phenotypes rather than discrete phenotypes as studied by Mendel
Quantitative traits
Proportions of dominant alleles to recessive alleles in a large, random mating population will remain same from generation to generation in the absence of forces that change those proportions
Hardy-Weinberg law
Random loss of alleles can occur if individuals do not mate as often
Small populations
Most significant cause of exception to H-W
Selection
