Test #1 Flashcards
Pass (Not Optional)
What are the building blocks of DNA?
Nucleotides
Nucleotides consist of a phosphate group, a sugar, and a nitrogenous base.
What are the four types of nitrogenous bases in DNA?
- Adenine
- Thymine
- Cytosine
- Guanine
These bases pair specifically: Adenine with Thymine, and Cytosine with Guanine.
What is a karyotype?
A visual representation of an individual’s chromosomes
Karyotypes can be used to identify chromosomal abnormalities.
What is the difference between diploid and haploid?
Diploid (2n) has two sets of chromosomes, haploid (n) has one set
Diploid cells are typically somatic cells, while haploid cells are gametes.
What are genetic disorders often caused by?
Errors in chromosomes
These can result from mutations, deletions, or duplications.
Define genotype.
The genetic makeup of an individual
Genotype determines potential traits but may not always be expressed.
Define phenotype.
The physical expression of a genotype
Phenotype can be influenced by environmental factors.
What is a gamete?
A reproductive cell (sperm or egg)
Gametes are haploid and combine during fertilization to form a zygote.
What is a zygote?
The fertilized egg formed from the union of two gametes
The zygote is diploid, containing genetic material from both parents.
What does heterozygous mean?
Having two different alleles for a trait
For example, Aa is heterozygous for a gene.
What does homozygous mean?
Having two identical alleles for a trait
For example, AA or aa are homozygous for a gene.
What is a purebred organism?
An organism that is homozygous for a trait
Purebreds produce offspring with the same traits.
What is a hybrid organism?
An organism that is heterozygous for a trait
Hybrids result from the crossing of different purebred lines.
Define homologous chromosomes.
Chromosomes that are similar in shape, size, and genetic content
Homologous chromosomes pair during meiosis.
What is an allele?
A variant form of a gene
Alleles can be dominant or recessive.
What is the difference between dominant and recessive alleles?
Dominant alleles express their traits over recessive alleles
A dominant allele masks the effect of a recessive allele in heterozygotes.
What is the law of segregation?
The principle that alleles for a trait separate during gamete formation
This ensures that offspring receive one allele from each parent.
What is the law of independent assortment?
The principle that genes for different traits are inherited independently of each other
This applies when genes are located on different chromosomes.
What is crossing over?
The exchange of genetic material between homologous chromosomes during meiosis
This increases genetic variation in offspring.
What is a monohybrid cross?
A genetic cross that considers one trait
It typically involves a single pair of contrasting traits.
What is a test cross?
A cross between an individual with an unknown genotype and a homozygous recessive individual
This determines the genotype of the unknown individual.
What is a dihybrid cross?
A genetic cross that considers two traits
It examines the inheritance of two different genes.
What is a Punnett square?
A diagram used to predict the genotypes of offspring from a genetic cross
It visually represents the possible combinations of alleles.
What are phenotypic ratios?
Ratios that describe the relative frequencies of different phenotypes in offspring
Common ratios include 3:1 for monohybrid crosses.
