AP Bio 5.5 Chromosomal Inheritance
38 flashcards covering AP Bio 5.5 Chromosomal Inheritance for the AP-BIOLOGY Unit 5 section.
Chromosomal inheritance is a fundamental concept in genetics that describes how traits are passed from parents to offspring through chromosomes. This topic is outlined in the College Board's AP Biology Curriculum Framework, specifically under Unit 5, which focuses on the molecular basis of heredity and the mechanisms of genetic transmission. Understanding chromosomal inheritance is crucial for grasping how genetic variations occur and how they can influence phenotypes.
In practice exams and competency assessments, questions on chromosomal inheritance often involve predicting offspring genotypes and phenotypes based on parental genetic information. Common question styles include Punnett squares, pedigree analysis, and scenarios involving linked genes. A frequent pitfall students encounter is misunderstanding the difference between autosomal and sex-linked inheritance, which can lead to incorrect predictions about trait inheritance patterns.
One practical tip is to always consider the possibility of incomplete dominance or codominance when analyzing genetic crosses, as these can significantly alter expected outcomes.
Terms (38)
- 01
What is the chromosomal theory of inheritance?
The chromosomal theory of inheritance states that genes are located on chromosomes and that the behavior of chromosomes during meiosis and fertilization accounts for inheritance patterns (College Board AP CED).
- 02
How many chromosomes do humans have?
Humans have 46 chromosomes, arranged in 23 pairs, with one chromosome of each pair inherited from each parent (College Board AP CED).
- 03
What is the role of meiosis in genetic variation?
Meiosis reduces the chromosome number by half and allows for genetic recombination through crossing over and independent assortment, leading to genetic variation in gametes (College Board AP CED).
- 04
Define homologous chromosomes.
Homologous chromosomes are pairs of chromosomes that have the same genes at the same loci but may have different alleles (College Board AP CED).
- 05
What is the significance of crossing over during meiosis?
Crossing over during meiosis allows for the exchange of genetic material between homologous chromosomes, increasing genetic diversity in offspring (College Board AP CED).
- 06
When does independent assortment occur?
Independent assortment occurs during metaphase I of meiosis when homologous chromosomes are randomly distributed to daughter cells (College Board AP CED).
- 07
What is a karyotype?
A karyotype is a visual representation of an individual's chromosomes, arranged in pairs and organized by size and shape, used to identify chromosomal abnormalities (College Board AP CED).
- 08
How does nondisjunction affect gametes?
Nondisjunction is the failure of homologous chromosomes or sister chromatids to separate properly during meiosis, leading to gametes with an abnormal number of chromosomes (College Board AP CED).
- 09
What is the result of fertilization between two gametes with abnormal chromosome numbers?
Fertilization between gametes with abnormal chromosome numbers can lead to aneuploidy, which is an abnormal number of chromosomes in the zygote (College Board AP CED).
- 10
Define aneuploidy.
Aneuploidy is a condition in which there is an abnormal number of chromosomes in a cell, which can result from nondisjunction during meiosis (College Board AP CED).
- 11
What is the difference between genotype and phenotype?
Genotype refers to the genetic makeup of an organism, while phenotype is the observable physical or biochemical characteristics resulting from the genotype (College Board AP CED).
- 12
What is a Punnett square used for?
A Punnett square is a diagram used to predict the genotypes and phenotypes of offspring from a genetic cross (College Board AP CED).
- 13
What are sex-linked traits?
Sex-linked traits are traits that are associated with genes located on sex chromosomes, often affecting males and females differently due to the presence of X and Y chromosomes (College Board AP CED).
- 14
How does the environment influence gene expression?
The environment can influence gene expression through factors such as temperature, nutrition, and exposure to toxins, leading to variations in phenotype (College Board AP CED).
- 15
What is the purpose of genetic mapping?
Genetic mapping is used to determine the location of genes on chromosomes and the distances between them, which can help in understanding inheritance patterns (College Board AP CED).
- 16
Define epistasis.
Epistasis is a genetic interaction where the effect of one gene is masked or modified by one or more other genes, influencing the phenotype (College Board AP CED).
- 17
What is the role of telomeres in chromosomes?
Telomeres are repetitive sequences at the ends of chromosomes that protect them from degradation and prevent them from fusing with other chromosomes (College Board AP CED).
- 18
What is a test cross?
A test cross is a breeding experiment used to determine the genotype of an individual with a dominant phenotype by crossing it with a homozygous recessive individual (College Board AP CED).
- 19
What is the principle of segregation?
The principle of segregation states that during gamete formation, the two alleles for a gene segregate from each other so that each gamete carries only one allele for each gene (College Board AP CED).
- 20
How can mutations affect inheritance?
Mutations can introduce new alleles into a population, potentially affecting inheritance patterns and leading to variations in traits (College Board AP CED).
- 21
What is the significance of polygenic inheritance?
Polygenic inheritance involves multiple genes contributing to a single trait, resulting in a continuous range of phenotypes, such as height or skin color (College Board AP CED).
- 22
What is a dihybrid cross?
A dihybrid cross is a genetic cross that examines the inheritance of two different traits, allowing for the analysis of the independent assortment of alleles (College Board AP CED).
- 23
Define codominance.
Codominance occurs when both alleles in a heterozygous individual contribute equally and visibly to the phenotype, such as in blood type AB (College Board AP CED).
- 24
What is the role of the SRY gene?
The SRY gene, located on the Y chromosome, is responsible for the development of male characteristics during embryonic development (College Board AP CED).
- 25
How does a pedigree chart help in genetics?
A pedigree chart is used to trace the inheritance of traits through generations, helping to determine the mode of inheritance and identify carriers of genetic disorders (College Board AP CED).
- 26
What is the significance of linked genes?
Linked genes are genes that are located close to each other on the same chromosome and tend to be inherited together, affecting inheritance patterns (College Board AP CED).
- 27
What is the purpose of DNA replication in inheritance?
DNA replication is essential for inheritance as it ensures that each daughter cell receives an identical copy of the genetic material during cell division (College Board AP CED).
- 28
How do mutations contribute to evolution?
Mutations introduce genetic variation into a population, which can be acted upon by natural selection, driving the process of evolution (College Board AP CED).
- 29
What is the difference between complete dominance and incomplete dominance?
Complete dominance occurs when one allele completely masks the effect of another, while incomplete dominance results in a blended phenotype in heterozygous individuals (College Board AP CED).
- 30
What is the role of RNA in gene expression?
RNA plays a crucial role in gene expression by serving as a template for protein synthesis and regulating gene activity (College Board AP CED).
- 31
Define genetic drift.
Genetic drift is a mechanism of evolution that involves random changes in allele frequencies within a population, often having a greater effect in small populations (College Board AP CED).
- 32
What is a phenotypic ratio?
A phenotypic ratio is the relative number of different phenotypes produced in a genetic cross, typically expressed as a ratio (e.g., 3:1) (College Board AP CED).
- 33
How does natural selection relate to chromosomal inheritance?
Natural selection acts on phenotypic variations that arise from chromosomal inheritance, favoring traits that enhance survival and reproduction (College Board AP CED).
- 34
What is the purpose of genetic engineering?
Genetic engineering involves manipulating an organism's DNA to achieve desired traits, such as increased resistance to diseases or improved nutritional content (College Board AP CED).
- 35
What is a recessive allele?
A recessive allele is an allele that is masked by the presence of a dominant allele in a heterozygous individual and only expressed in a homozygous recessive condition (College Board AP CED).
- 36
What is the role of the X chromosome in sex-linked traits?
The X chromosome carries many genes unrelated to sex, and because males have only one X chromosome, they are more likely to express recessive traits linked to it (College Board AP CED).
- 37
How does fertilization restore the diploid state?
Fertilization restores the diploid state by combining two haploid gametes, resulting in a zygote with the full set of chromosomes (College Board AP CED).
- 38
What is the significance of the Hardy-Weinberg principle?
The Hardy-Weinberg principle provides a mathematical model to study genetic variation in a population, predicting allele and genotype frequencies under ideal conditions (College Board AP CED).