Genetics Flashcards
Alleles
Different form of genes associated with particular characteristics
Chromosomes
Hereditary units of an organism
Locus
Particular point where a certain gene is found on a chromosome
Homozygous
An individual with two of the same alleles on a homologous chromosome
Hertrozygous (hybrid)
An individual with contrasting alleles for the same trait on a homologous chromosome
Parental generation
The two original organism being crossed
First filial generation
The first generation of offspring from
The parent
Second filial generation
Generation of offspring arising from the first filial generation
Law of Dominance
- pattern of heredity in which one gene of an alleluic pair is expressed
- this in the heterozygous condition, one allele of a gene may express itself and mask the presence of the other allele
Dominant trait
The trait or allele that is expressed
Recessive
The trait or allele that is present but is not expressed
Progeny
Offspring
Siblings
Brothers or sisters
Punnett square
Used to represent genetic crosses
Genotype
The genetic makeup of an organism based upon alleles
Phenotype
The appearance of an organism
Genes
Factors that control organism traits
-the part of the DNA molecule containing the genetic code
Principle of segregation and recombination
When gametes are formed during meiosis there is a random segregation of homologous chromosomes
- crossing over
- as a result of fertilization alleles recombined as a consequence a new allylic gene culmination are likely to produce
Law of independent assortment
If genes for two different traits are located on a different chromosomes, they are segregated randomly during meiosis and therefore may be inherited independently of each other
Incomplete dominance
A case of contrasting alleles in which one one allele is only particular dominay over the other
- The dominant allele is particularly express when a recessive allele is present
- sometimes called blending inheritance
Codominance
Case of contrast no alleles in which neither will dominate over the other
—alleles have an equal power
Gene linkage
Genes for two different traits are located on the same pair of chromosomes
-linked genes are usually inherited together
Crossing over
during synapsis in the first meiotic division, the chromatids in a
homologous pair of chromosomes often twist around each other, break, exchange segments and rejoin.
Karyotype
And in large photograph of the chromosomes in organism
Mutations
Change in genetic material
Non disjunction
homologous chromosomes fail to separate during meiosis, producing offspring with one chromosome more or less than is normal
Disjunction
the separation of homologous chromosomes during meiosis
Polyploidy
• The presence of one or more entire additional sets of chromosomes in an organism (3n,4n number, etc.)
Mutantic agents
increase the random incidence of mutations
- Radiation – X-rays, ultraviolet, radioactive substances, and cosmic rays
- Chemicals – formaldehyde, benzene, asbestos fibers, THC, nicotine
Artificial selection
– individuals with desirable traits are mated to produce offspring with those
Inbreeding
– offspring produced by artificial selection are mated with one another to reinforce those desirable traits
Hybridization
with different desirable traits to produce offspring with
a combination of both desirable traits
Recombinant DNA (genetic engineering)
new varieties of plants and animals can be created by manipulating the genetic instructions of these organisms to produce new characteristics
Translocation
transfer of one section of a chromosome to a nonhomologous chromosome
Addition
A portion of one chromosome is transferred to another
Inversion
a portion of a chromosome breaks off and then becomes reattached to the same chromosome in an inverted (upside down) fashion
