CHAPTER 1 - P1 Flashcards
The attempt to understand biological phenomena in molecular terms
Molecular Biology
The study of gene structure and function at the molecular level.
Molecular Biology
Early work on genes which is not considered as molecular biology or molecular genetics because early geneticists didn’t know the molecular nature of genes hence it is called ________
transmission genetics.
Deals with the transmission of traits from parental organisms to their offspring.
transmission genetics.
1944 - chemical composition of _____ was known.
genes
1865 - Gregor Mendel published his findings on the _____________
inheritance of seven different traits in the garden pea.
inheritance is ________ — each parent contributes particles, or genetic units, to the offspring which is called the _____
particulate ; genes
appearance or set of observable characteristics of an organism.
Phenotype
(MENDEL’S LAWS OF INHERITANCE) gene in different forms.
Alleles
In inheritance of seven different traits in the garden pea, allele for _________ was dominant when he mated a green- seeded pea with a yellow-seeded pea.
yellow seeds
In inheritance of seven different traits in the garden pea, All of the progeny in the F1 or first filial generation had _____ and when the F1 yellow peas were allowed to self-fertilizie, some _______ peas reappeared.
yellow seeds ; green-seeded
ratio of yellow to green seeds in the second filial generation (F2) was very close to ____
3:1
Filial = filius, ___ and filia, ______
son ; daughter
_____ = first filial generation containing sons and daughters of the original parents.
F1
_____ = second filial generation containing the offspring of the F1 individuals.
F2
Mendel concluded that the allele for green seeds must have been ________, even though it didn’t affect seed color of those peas.
preserved in the F1 generation
According to mendel, the parents were ______ — each parent plant carried 2 copies of the gene. In this concept, ______ have two copies of the same allele (either 2 alleles for yellow seeds or 2 allleles for green seed) while _____ have one copy of each allele.
diploid ; homozygotes ; heterozygotes
In the study of mendel, the two parents in the first mating were _____; the resulting F1 peas were all _______. Further, Mendel reasoned that sex cells contain only one copy of the gene; that is, they are ____. Homozygotes can therefore produce sex cells, or gametes, that have only one allele, but heterozygotes can produce gametes having either allele
homozygotes ; heterozygotes ; haploid.
Mendel’s work was unrecognized or ignored until 1900 when the three botansists had arrived at similar conclusions idependently and rediscovered it.
THE CHROMOSOME THEORY OF INHERITANCE
Mendel had predicted that gametes would contain only one allele of each gene instead of two. If chromosomes carry the genes, their numbers should also be ____ by half in the gametes.
reduced
______ therefore appeared to be the discrete physical entities that carry the genes.
Chromosomes
__________ the notion that chormosomes carry genes.
“Chromosome Theory of Inheritance”
Remained skeptical of the chromosome theory idea.
Thomas Hunt Morgan
Thomas Hunt Morgan, in 1910, he provided the first definitive evidence for the __________
chromosome theory
Thomas Hunt Morgan, worked with the ____ (___________) which is a convenient organism that is small in size, have short generation time and large number of offspring.
fruit fly ; Drosophila melanogaster
THM…
He mated red-eyed flies (dominant) with white- eyed flies (recessive), most, but not all, of the F1 progeny were _______.
He then mated the red-eyed males of the F1 generation with their red-eyed sisters and they produced about ________
red-eyed ; one-quarter white-eyed males with no white-eyed females.
The eye color phenotyope was said to be ______ as sex and eye color in the study are transmitted together because the genes governing these characteristics are located on the same chromosome which is the _______
sex- linked ; X chromosome
Every gene has its place, or _____, on a chromosome. The figure depicts a hypothetical chromosome and the positions of its 3 genes called the ________.
locus ; A, B and C
Diploid organisms such as human beings normally have _____ of all chromosomes (except ______) which means that they have 2 copies of most genes and the copies can be the same alleles (_______) or different alleles (________)
two copies ; sex chromosomes ; homozygous ; heterozygous
shows a diploid pair of chromosomes with different alleles at one locus (Aa) and the same alleles at the other two loci (BB and cc) where the genotype or allelic constitution of the organisms with respect to the three genes is AaBBcc.
Because this organism has two different alleles (A and a) in its two chromosomes at the A locus, it is ______ at that locus (Greek: hetero, meaning different).
Since it has the same, dominant B allele in both chromosomes at the B locus, it is _______ at that locus (Greek: homo, meaning same).
And because it has the same, recessive c allele in both chromosomes at the C locus, it is __________ there.
Since the A allele is dominant over the a allele, the phenotype of this organism would be the dominant phenotype at the A and B loci and the recessive phenotype at the C locus.
heterozygous ; homozygous dominant ; homozygous recessive
Another Morgan’s genetic concept.
Wild Type Vs. Mutant
a phenotype that is most common or at least the generally accepted standard, phenotype of an organism also called standard type. In the case of Drosophila, red eys and full- size wings are _______
Wild-Type
the least common type that are a result of mutation. In the case of drosophila, it is white eyes and miniature wings. ______ are usually recessive but not always.
Mutant ; mutant alleles
Genes on separate chromosomes behave _______ in genetic experiments while genes on the same chromosome (eg. miniature wing and white eye) behave as if they are ______
independently ; linked
Genes on the same chromosome usually don’t show perfect _____such as in the study of morgan, although white and miniature are both on the X chromosome, they remain linked in offspring only _____ of the time
genetic linkage ; 65.5%
Other offspring have a new combination of allleles not seen in the parents are called _______
recombinants.
The recombinants are produced in ______ between the chromosomes that carry the same genes or alleles of the same genes or what is called _______.
crossing over ; homologous chromosomes
In the case of the drosophila, during formation of eggs in the female, an X chromosome bearing the white and miniature alleles experienced ______ with a chromosome bearing the red eye and normal wing alleles.
crossing over