Genetics Flashcards
What is the definition of phenotype?
The physical expression or characteristics of an organism, influenced by genotype and environmental factors
Examples include eye color, height, and hair color.
What is the definition of genotype?
The genetic makeup of an organism; the combination of alleles for a particular gene
Examples include AA, Aa, aa.
What does homozygous mean?
Both alleles for a given trait are the same
Examples include AA or aa.
What does heterozygous mean?
The two alleles for a given trait are different
Example: Aa.
What is the Law of Segregation?
Each organism has two alleles for each trait, which separate during gamete formation
Each gamete carries only one allele for each gene.
What is the Law of Independent Assortment?
Genes located on different chromosomes are inherited independently of each other
This leads to genetic variation in offspring.
What is the classic ratio for a monohybrid cross?
3:1 (dominant: recessive phenotype)
This occurs in a cross between two heterozygous organisms.
What is the typical ratio for a dihybrid cross?
9:3:3:1
This ratio represents the phenotypes for two traits in a cross between two heterozygous organisms.
What is a dominant allele?
An allele that is expressed in the phenotype when present
Example: A.
What is a recessive allele?
An allele that is only expressed in the phenotype when two copies are present
Example: aa.
What is incomplete dominance?
Neither allele is completely dominant, resulting in a blend of traits
Example: red flower crossed with white flower produces pink flowers.
What is co-dominance?
Both alleles are fully expressed in the phenotype
Example: AB blood type where both A and B alleles are visible.
What are autosomal traits?
Traits found on non-sex chromosomes
Examples include eye color and hair color.
What are sex-linked traits?
Traits found on sex chromosomes, often affecting males more than females
Examples include color blindness and hemophilia.
What is a carrier in genetics?
An individual with one recessive allele for a genetic trait and one dominant allele
Example: A carrier for cystic fibrosis is heterozygous (Ff) but does not show symptoms.
What are multiple alleles?
More than two alleles exist for a given gene
Example: The human ABO blood system has three possible alleles: A, B, and O.
What are the possible genotypes for the ABO blood system?
- AA
- AO
- AB
- BB
- BO
- OO
A and B are dominant, while O is recessive.
What is a monohybrid cross?
A cross between two individuals focusing on one trait
Example: Aa × Aa.
What is a dihybrid cross?
A cross between two individuals focusing on two traits
Example: AaBb × AaBb.
What is a pedigree?
A diagram used to track traits through generations
Squares represent males, circles represent females.
What is the structure of DNA?
A double-helix made up of nucleotides
Each nucleotide contains a sugar (deoxyribose), a phosphate group, and a nitrogenous base.
What are the base pairing rules in DNA?
A pairs with T, and C pairs with G
Strands are anti-parallel.
What is DNA replication?
The process by which DNA makes a copy of itself
Involves helicase, DNA polymerase, and ligase.
What is transcription in protein synthesis?
DNA is used as a template to make mRNA
RNA polymerase binds to DNA to synthesize mRNA.
What is translation in protein synthesis?
mRNA is translated into an amino acid sequence at the ribosome
tRNA brings amino acids that match mRNA codons.
What is a point mutation?
A single nucleotide is altered
Example: sickle cell anemia.
What is a substitution mutation?
One base is replaced by another
What is an insertion mutation?
An extra base is added
What is a deletion mutation?
A base is removed
What is a frameshift mutation?
Insertion or deletion of nucleotides shifts the reading frame
Often results in a nonfunctional protein.
What are chromosomal mutations?
Deletions, duplications, inversions, or translocations of large portions of chromosomes
What is amniocentesis?
A procedure where a sample of amniotic fluid is taken to test for genetic disorders
Example: Down syndrome.
What is a karyotype?
A visual representation of an individual’s chromosomes
Used to detect chromosomal abnormalities.
What is mitosis?
The process by which somatic cells divide, resulting in two identical daughter cells
Phases include Prophase, Metaphase, Anaphase, Telophase, and Cytokinesis.
What is meiosis?
The process by which gametes are formed, involving two rounds of division
Results in four non-identical daughter cells.
What is the genetic significance of mitosis?
Essential for growth, repair, and asexual reproduction
Produces genetically identical cells.
What is the genetic significance of meiosis?
Essential for sexual reproduction, producing gametes with genetic variation
Ensures genetic diversity and maintains chromosome number across generations.
