Chapter 13 Flashcards
Genetics and Molecular biology
transposition
movement of a piece of chromosome to another chromosomal location
transposable genetic element
a “jumping gene” , DNA fragment that can move to a new location on the same chromosome or even to another chromosome
Molecular genetics
studies the function and structure of genes at a molecular level
Chromosomes are composed of two types of large molecules:
DNA and protein
a DNA molecule is made of a chain of ___________
nucleotides
each nucleotide consists of 3 parts
- a nitrogen containing compound called a BASE
- a 5-carbon sugar called DEOXYRIBOSE
- a phosphate group
four types of nucleotides occur in DNA
- Adenine (A)
- Guanine (G)
- Cytosine (C)
- Thymine (T)
Name the purines
Adenine (A), and Guanine (G)
Girls Are PURe
name the pyrimidines
Cytosine (C) and Thymine (T)
what are the pairs of bases in DNA?
Guanine and Cytosine G=C
Adenine and Thymine A=T
The DNA in a cell must perform 4 major tasks
- store genetic information
- copy that information for future generations of cells
- express that information
- occasionally change its message, or MUTATE
Most DNA in plants resides in the _______
nucleus
About ______ mutations occur with each cell division
4,000
During transcription
a copy of the gene message is made using RNA building blocks
During transcription, Thymine is replaced by
Uracil
When transcription is complete,
RNA travels to the cytoplasm, where translation occurs
during translation,
the RNA message provides the information necessary to construct proteins
three different types of RNA are made by
transcription
the three types of RNA made by transcription and their functions
messenger RNA (mRNA): translated to produce proteins transfer RNA (tRNA): machinery used to translate mRNA ribosomal RNA (rRNA): machinery used to translate mRNA
RNA polymerase
responsible for assembling the RNA strand
In most eukaryotes, less than 10% of the DNA in the genome contains genes, the rest is …….
noncoding DNA
At the beginning of every gene, a DNA sequence called a ________ ______ acts as a signal flag
promoter region
what does the promoter region act as?
it acts as a signal flag to indicate to the machinery scanning the DNA that a gene is ahead
A __________ DNA sequence at the end of each gene ___________
terminator, signals the transcription enzymes to fall off the DNA molecule
A transcript is a
single stranded RNA molecule
anticodon
a sequence of three nucleotides that recognizes a codon on mRNA and base pairs with it
Ribosomes
act as workbenches during protein synthesis
mutation
changes in a DNA sequence
mutagens
can alter DNA sequences
mutations are either _______ or ________
somatic or germ-line
somatic mutation
occurs in a body cell and will exist in all cells produced by mitosis of the mutant cell
somatic mutations may show up as a _____
sport, or a branch that looks different from the others on a plant
Germ line mutation
occurs in tissue that will produce gametes, or sex cells
unlike somatic mutations, germ line mutations will be passed on to future generations through _____
seeds
Cytogenetics
the study of chromosome behavior and structure from a genetic point of view
inversion
results when a piece of chromosome is broken and reinserted in the opposite orientation
translocation
occurs when a piece of a chromosome breaks off and becomes attached to another one
speciation
formation of a new species
polyploid
a plant that has at least one set of chromosomes
Gregor Mendel was an Austrian monk who studied
pea plants
parental generation
original plants in making the crosses
filial generation
the parental generation’s first offspring
offspring of the filial generation are called
second filial generation
law of unit characters
factors, which always occur in pairs, control the inheritance of traits
alleles
paired factors of genes
locus
genes are always at the same position (LOCUS) on a chromosome
Law of dominance
for any given pair of alleles, one may mask the expression of the other
the expressed allele is referred to as
dominant
the allele that is masked, or not expressed is
recessive
phenotype
refers to the physical appearance of the organism
genotype
refers to the genetic information responsible for contributing to that phenotype
Homozygous
both alleles of a pair are identical
Ex: GG
Heterozygous
the pair is composed of contrasting alleles
Ex: Gg
Monohybrid cross
a cross is made between two true-breeding parents differing for that trait, producing an F1 generation, then, these F1 plants are intercrossed to produce an F2 generation
Dihybrid cross
crossing the F2 generation with itself
the law of independent assortment
the factors (genes) controlling two or more traits segregate independently of each other
genes that do not segregate independently are said to be
linked
Punnett Square
a diagram used to determine the genotypes of zygotes
backcross
a cross between a hybrid and one of its parents
testcross
cross between a plant with the dominant phenotype and a homozygous recessive plant
incomplete dominance
absence of dominance, Ex: pink snapdragons
Quantitative traits
exhibit a range of phenotypes, Ex: fruit yield
quantitative trait loci
Chromosomal fragments that contain genes that influence the the trait and behave like Mendelian genes
extranuclear DNA is found in
both mitochondria and chloroplasts
endosymbiotic theory
mitochondria and chloroplasts were free living bacteria at some time in their evolutionary history
maternal inheritance
extra nuclear genes are typically passed on by the female parent
map unit
equals 1% crossing over between a pair of genes
Hardy Weinberg Law
states that the proportions of dominant alleles to recessive ones in a large, random mating population will remain the same from generation to generation unless there are forces that change those proportions.
