11. Human Genetics Unit Flashcards
What is a gene?
A DNA sequence that encodes a protein and determines a character.
What is a chromosome?
A structure of condensed chromatin carrying genetic information in the form of genes.
What is the human genome?
The total genetic content of an organism.
How many chromosomes do somatic cells have?
46 chromosomes or 23 pairs.
What are autosomes?
The 22 pairs of non-sex chromosomes.
What are the sex chromosomes for males and females?
XX for females, XY for males.
What is the central dogma of molecular biology?
DNA is transcribed into RNA, which is translated into protein.
What is a codon?
A triplet of nucleotides that codes for a specific amino acid.
What is mitosis?
Division of somatic cells to produce two identical diploid daughter cells.
What is meiosis?
Division of germ cells to produce four genetically different haploid gametes.
What happens during prophase of mitosis?
Chromatin condenses into chromosomes and the nuclear envelope breaks down.
What happens during metaphase of mitosis?
Chromosomes align at the metaphase plate.
What happens during anaphase of mitosis?
Chromatids separate and move to opposite poles.
What happens during telophase of mitosis?
Chromosomes decondense, nuclear envelope reforms, and cytokinesis occurs.
What are the two sources of genetic variation in meiosis?
Crossing over and independent assortment.
What is crossing over?
Exchange of genetic material between non-sister chromatids during prophase I of meiosis.
What is independent assortment?
Random alignment of homologous chromosomes during metaphase I.
What is a genotype?
The genetic makeup of an organism (e.g., AA, Aa, or aa).
What is a phenotype?
The observable physical traits resulting from genotype and environment.
What is a dominant allele?
An allele that masks the expression of another allele.
What is a recessive allele?
An allele whose effects are masked by a dominant allele.
What is homozygous?
Having two identical alleles for a trait (AA or aa).
What is heterozygous?
Having two different alleles for a trait (Aa).
What is autosomal dominant inheritance?
A pattern where one copy of the dominant allele causes the trait to be expressed.
What is autosomal recessive inheritance?
Trait expressed only when two copies of the recessive allele are present.
What is X-linked inheritance?
Traits associated with genes on the X chromosome, often affecting males more.
What causes sickle-cell anemia?
A point mutation that changes one amino acid in hemoglobin.
What is phenylketonuria (PKU)?
A recessive disorder where phenylalanine cannot be metabolized, causing neurotoxicity.
What is Tay-Sachs disease?
A recessive disorder causing lipid buildup in neurons, leading to neurodegeneration.
What is Huntington’s disease?
A dominant neurodegenerative disorder with onset in midlife.
What is nondisjunction?
Failure of chromosomes to separate properly during meiosis.
What is Down syndrome?
Trisomy 21, characterized by developmental delays and physical traits.
What is Turner syndrome?
Monosomy X (45, XO); females with incomplete sexual development and infertility.
What is Klinefelter syndrome?
47, XXY; males with infertility, breast development, and learning difficulties.
