Genetics Flashcards
History of genetics (father?)
Gregor Mendel- Pure breed Pea plants, investigated height, shape colour
tall and short homozygous breed
F1 all tall
F2 one short and 3 tall
Discovery of dominant and recessive genes
What does inheritance result to?
differences and similarities between offspring and parent
Define chromosomes
long thread like dna strands wond up around histones
define chromatin
network of threadlike structures made up of chromosomal material such as DNA RNA and histone proteins
define genome
complete set of genetic instructions (genes) required to create an organism
Define genes
sections of dna that code for heridaty characteristics
How are cells given their character?
different genes are activated to produce specific proteins
Define alleles
variations of a gene, different versions of the same gene at the same locus in a homologous chromosome
Meiosis/ fertilization in terms of alleles?
Meiosis sperates homologous chromosomes so one allele of each gene pair is present in the gamete
fertilization creates a zygote with on allele from each parent to create pair of alleles
Mendels law of segregation?
states that the characteristics of an organism are controlled by pairs of alleles which separate into different gametes during meiosis. one allele of each gene pair will be present in the gamete.
Genotype Vs Phenotype?
genotype is genetic make up of an organism
phenotype is physical appearance of an organism (also environment)
Dominant allele Vs recessive allele?
Dominant allele is expressed in phenotype while recessive allele supressed in the presense of a dominant allele and not expressed unless dominant allele is not present
Mendels law of dominance?
states that in a cross between two parents that are pure for contrasting traits. only the dominant trait will be expressed in the phenotype of the offspring. recessive allele will always be masked by dominant allele
Homozygous vs Heterozygous?
homozygous is pair of alleles at a locus are the same for a characterisitic
heterozygous is pair of alleles at a locus are the different for a characterisitic
What does a genetic diagram show and give format
shows genotype and phenotype in a cross between parents
Charceteristic
key
P1 Phenotype genotype
meiosis
Gametes:
Fertlization
Punnet Sqaure
F1: Genotype Phenotype
Ratio
What is a monohybrid cross?
cross between two parents with different alleles for a single gene
3 types of dominance and explain?
complete- dominant expressed and recessive supressed in heterozygous
incomplete- Cross will result in an intermediate phenotye (blend)
co dominance- Both Traits expressed fully and equally in the phenotype
How to use test crosses?
Organism has a dominat charcteristic
cross with a homozygous recessive organism
if any of the offspring show the recessive triat then organism was heterozygous
Which sex chromosome is longer Male vs female genotypes?
X chromosome longer
Y chromosome shorter and comes from father
XY male and XX female
Why does a male embryo develop?
The Y chromosome from the sperm cell has gene cose for gonad tissue which develops into testis to form male whereas females will develop ovaries
Why do sex linked disorders affect males?
The mutation occurs on the part of the X chromosome that does not have a homologous pair and as males only have one X Chromosome from mother they cannot carry the normal allele so the recessive mutated allele is expressed
Explain Heamophilia?
Disorder which causes excessive frequent bleeding and blood cannot clot correctly as a result of a mutation on the part of the X chromosome which codes for blood clotting from mother
Explain red green colour blindness
Mutation on the gene that codes for photopigments to see red and green colours on X chromosome, confusion of red and green hues and affects more males and they only have one X chromosome
What are multiple alleles?
more than two alleles for a particular gene characteristic ( one person will only have two alleles for any charcateristic)
