Biology slides 9
What are characteristics in organisms?
Physiological feaetures such as hair colour and eye colour.
What do traits represent in genetics?
The version of a given characteristic expressed by an organism, also known as phenotypes.
What are alleles?
Different versions of a gene that represent various traits.
What causes differences between alleles?
Mutations.
What does it mean if an organism is homozygous?
It has two identical alleles for a given character.
What does it mean if an organism is heterozygous?
It has two different alleles for a given character.
What is a genotype?
The combination of alleles an organism has.
Who is considered the father of genetics?
Gregor Mendel.
What is true-breeding?
Breeding organisms with a specific trait so that all offspring consistently display that trait.
What is hybridization in genetics?
Breeding two different true-bred organisms.
What is the parental (P) generation?
The organisms initially bred together.
What is the first filial (F1) generation?
The offspring from the initial breeding.
What is the F2 generation?
The offspring produced when organisms within the F1 generation are crossed.
What ratio of phenotypes did Mendel observe in the F2 generation?
A specific 3:1 ratio.
What are dominant alleles?
Alleles that express their phenotype even if only one copy is present.
What are recessive alleles?
Alleles that express their phenotype only if the organism is homozygous for that allele.
What notation is used for dominant and recessive alleles?
Uppercase letters for dominant alleles and lowercase letters for recessive alleles.
What is the Law of Segregation?
A diploid parent will only pass on one of the two alleles they possess.
What is a Punnett Square used for?
To represent possible outcomes of genetic crosses.
What is a Test Cross?
A cross between a dominant phenotype and a recessive phenotype to determine the genotype of the dominant organism.
What does it indicate if one sibling is not near-sighted in a family where near-sightedness is dominant?
At least one parent must be heterozygous for the near-sightedness trait.
What is a dihybrid cross?
A genetic cross that examines the inheritance of two different traits simultaneously.
What does the Law of Independent Assortment state?
Alleles for one character are inherited independently of alleles for another character.
What is the significance of a locus in genetics?
A locus is the specific location of a gene on a chromosome.
What does Mendel's law of segregation state?
Paired unit factors (genes) must segregate equally into gametes, giving offspring an equal likelihood of inheriting either factor.
What is the phenotypic ratio in the F2 generation of a dihybrid cross?
The phenotypic ratio 9:3:3:1.
How do sex-linked inheritance patterns differ from autosomal inheritance?
Sex-linked inheritance involves genes located on sex chromosomes, leading to different inheritance patterns between males and females.
What symbols are used in pedigree charts to represent males and females?
Squares represent males, circles represent females, and diamonds represent non-binary/gender-diverse individuals.
What does it indiciate if a trait skips a generation in a pedigree?
It may suggest that the trait autosomal recessive.
What is the characteristic of X-linked dominant inheritance?
An affected father will pass the trait to all daughters but none of his sons.
What is a key feature of X-linked recessive inheritance?
It can skip generations and is more prevalent in males.
What does Y-linked inheritance imply?
Only males are affected, and all sons of an affected man will also be affected.
What is the role of pedigree charts in human genetics?
They help track inheritance patterns across multiple generations.
What does it mean if two affected individuals have unaffected offspring?
It may indicate that the trait is autosomal dominant.
What are the implications of alleles being written as superscripts on the X choromsome?
It indicates that the inheritance of traits linked to the X chromosome differs between males and females.
What is the purpose of using standardized pedigree nomenclature?
To ensure clarity and inclusivity in representing gender and sex in genetic counseling.
What does the term 'affected' mean in the context of pedigree charts?
Individuals marked as 'affected' display the phenotype being studied.
What does the term 'autosomal' refer to?
Genes located on non-sex chromosomes.
What is the significance of gamete formation in Mendelian genetics?
Gamete formation is where segregation and independent assortment of alleles occur.
What does a diamond symbol represent in a pedigree chart?
A diamond represents a non-binary or gender-diverse individual.
What is the expected outcome of a cross between two heterozygous individuals for a trait?
The expected outcome is a 3:1 phenotypic ratio in the offspring.
What does the term 'cooperative' refer to in the context of studying human genetics?
It refers to the challenges faced when humans do not readily participate in genetic testing or controlled breeding.
What is the role of fertilization in genetic crosses?
Fertilization recombines alleles at random, contributing to genetic diversity in offspring.
What does the term 'intersex' refer to in genetic nomenclature?
Individuals with variations in sex characteristics that do not fit typical definitions of male or female.
What is a trihybrid cross?
A genetic cross that examines the inheritance of three different traits simultaneously.