Disease States 1 chapter 4: Genes and Genetic Diseases

Vocabulary flashcards covering key terms and definitions from the Genes and Genetic Diseases lecture notes.

Genes

The basic unit of inheritance; a sequence of DNA on a chromosome that encodes a product (protein or RNA).

DNA (Deoxyribonucleic Acid)

Genetic material with a double helix structure; made of nucleotides (deoxyribose, phosphate, and bases A, G, C, T) that contain the code for proteins.

Chromosome

A DNA-containing structure in the nucleus that carries genes; the basic unit of inheritance.

Nucleotide

The subunit of DNA containing a sugar (deoxyribose), a phosphate group, and a nitrogenous base.

Purines

Adenine (A) and Guanine (G); larger bases in DNA.

Pyrimidines (DNA)

Cytosine (C) and Thymine (T); smaller bases in DNA.

Codon

Three base pairs in messengers RNA

Anticodon

A sequence on tRNA that is complementary to a corresponding mRNA codon.

mRNA (Messenger RNA)

RNA that carries genetic information from DNA to the ribosome for protein synthesis.

tRNA (Transfer RNA)

RNA that brings specific amino acids to the ribosome during translation; contains an anticodon.

rRNA (Ribosomal RNA)

RNA component of ribosomes; site of protein synthesis.

Transcription

Process by which RNA polymerase synthesizes RNA from a DNA template.

Translation

Process by which ribosomes synthesize a polypeptide using mRNA and tRNA.

Ribosome

The molecular machine where protein synthesis occurs.

Protein

A molecule made of one or more polypeptides; essential for structure and function.

Amino acids

Twenty building blocks of proteins.

Mutation

Inherited alteration of genetic material; can be a base pair substitution or a frameshift.

Base pair substitution (missense mutation)

One base pair is replaced by another, potentially altering an amino acid sequence.

Frameshift mutation

Insertion or deletion of base pairs that shifts the reading frame of the genetic code.

Mutagens

Agents (e.g., radiation, chemicals) that increase the frequency of mutations.

DNA replication

Process of copying DNA; DNA polymerase adds nucleotides and proofreads for accuracy.

From Genes to Proteins

DNA is transcribed to RNA in the nucleus; RNA is translated in the cytoplasm to form proteins.

RNA

Ribonucleic acid; usually single-stranded; contains uracil (U) instead of thymine (T).

Promoter

DNA site where RNA polymerase binds to initiate transcription.

Termination sequence

DNA sequence that signals the end of transcription.

Somatic cells

Body cells with 46 chromosomes (23 pairs); diploid.

Gametes

Sperm and egg cells with 23 chromosomes; haploid.

Meiosis

Formation of haploid cells from diploid cells.

Autosomes

The first 22 chromosome pairs; homologous in both sexes.

Sex chromosomes

The remaining chromosome pair (XX in females, XY in males).

Karyotype

Ordered display of a person's chromosomes by size and centromere location.

Euploidy

Normal multiples of the haploid chromosome number (e.g., euploidy includes triploidy and tetraploidy as multiples of 23).

Triploidy

Three copies of each chromosome (69 total); usually not compatible with life.

Tetraploidy

Four copies of each chromosome (92 total); usually not compatible with life.

Aneuploidy

Abnormal number of chromosomes that is not a multiple of 23.

Trisomy

Three copies of a chromosome; some (e.g., trisomy 21) can survive.

Monosomy

Only one copy of a chromosome; often fatal.

Down syndrome

Trisomy 21; about 1 in 800 live births; features include intellectual challenges and distinctive facial characteristics.

Trisomy X

Sex chromosome aneuploidy with three X chromosomes in a female (XXX); symptoms vary.

Turner syndrome

45,X; females with a single X chromosome; features include short stature and ovarian failure.

Klinefelter syndrome

Sex chromosome aneuploidy with at least one Y and two X chromosomes (e.g., 47,XXY); male with certain physical features.

Trisomy X vs Turner vs Klinefelter

Examples of sex chromosome aneuploidies illustrating variable phenotypes across sexes.

X-linked inheritance

Genetic disorders involving X and possibly Y chromosomes; includes X-linked recessive and X-linked dominant patterns.

X-linked recessive

Males more frequently affected; trait can be passed through carrier females; may skip generations.

X inactivation

Process in females to compensate for gene dosage from having two X chromosomes.

Consanguinity

Mating of related individuals (inbreeding); increases recurrence risk for recessive disorders.

Autosomal dominant inheritance

One mutated allele is enough to cause disease; 50% recurrence risk with affected parent.

Autosomal recessive inheritance

Two mutated alleles required for disease; higher risk with consanguinity.

Autosomal dominant recurrence risk

When one parent is affected, each child has a 50% chance of inheriting the disease.

Autosomal recessive recurrence risk

Risk depends on carrier status of both parents; increases with consanguinity.

Homozygous

Two identical alleles for a gene.

Heterozygous

Two different alleles for a gene.

Carrier

An individual heterozygous for a recessive allele; usually asymptomatic but can pass the allele to offspring.

Cri du chat syndrome

5p deletion syndrome; features include low birth weight, mental challenges, and microcephaly.

Deletions

Loss of DNA material from a chromosome.

Duplications

Extra genetic material on a chromosome.

Inversion

Chromosomal rearrangement where a segment is reversed; can affect offspring.

Mosaicism

Presence of two or more different karyotypes in cells of the same individual.

Promoter site

DNA region where RNA polymerase binds to start transcription.

Termination sequence

DNA signal that ends transcription.

Mendelian inheritance types

Autosomal dominant, autosomal recessive, X-linked dominant, and X-linked recessive patterns.

DNA polymerase

DNA replication enzyme

Mutugens

Agents that cause mutations in DNA.

mRNA

A type of RNA that conveys genetic information from DNA to the ribosome, where proteins are synthesized.

translation

protein is formed in the cytoplasm

Somatic cells

cells that are not reproductive

Autosomes

first 22 of the 23 pairs of chromosomes in humans that are not involved in determining sex.

male sex chromosome

XY

female sex chromosome

XX

centromere

The region of a chromosome where the two sister chromatids are joined with kinetochore and which is crucial during cell division for proper segregation of chromosomes.

Euploid cell

A cell with the correct number of chromosomes, typically an exact multiple of the haploid number, which is normal for a species.

Polyploid cell

A cell containing more than two paired sets of chromosomes, resulting in an increase in chromosome number beyond the diploid state.

Tripoidy

A genetic condition involving an extra set of chromosomes, resulting in three complete sets, leading to developmental abnormalities and typically non-viability.

Tetraploidy

has four copies of each chromosome

Aneuploidy

A genetic condition characterized by an abnormal number of chromosomes, where one or more chromosomes are added or lost, leading to conditions such as Down syndrome.

monosomy

A genetic condition where one chromosome is missing from a pair, resulting in an abnormal chromosomal count and leading to various developmental issues.

Turner syndrome

A genetic disorder caused by the presence of only one X chromosome in females, leading to a range of physical and developmental abnormalities such as short stature, infertility, and heart defects.

Klinefelter syndrome

A genetic disorder in males caused by the presence of one or more extra X chromosomes, leading to symptoms such as reduced testosterone levels, infertility, and physical traits like taller stature.

deletion

chromosome breakage or loss of DNA

Inversion

a chromosomal rearrangement where a segment of a chromosome is reversed end to end, potentially affecting gene expression and function.

inbreeding

the mating of closely related individuals which can increase the risk of genetic disorders.

X-linked inheritance

a type of genetic inheritance where genes are located on the X chromosome, often leading to disorders affecting mainly males.