Exam 1 Flashcards
What is genetics
The study of inherited traits and their variations and transmission.
Heredity
The transmission of traits and biological information between generations via genes.
Genes
Biochemical instructions which tell cells how to manufacture certain proteins. The basic units of heredity.
Genome
The complete set of genetic material for an organism, including non protein coding genes. Most cells contain 2 copies of the genome
Exome
The 1% of the genome that codes for proteins. Roughly 20,325 genes are in the exome and most disease-causing genes lie within the exome.
Traits
Physical characteristics which are produced by an interaction of genes and your environment.
Alleles
A form of a gene with a slight variation in the resultant protein.
Gene variants
Undetectable genetic mutations which do not alter protein function.
Mendelian trait
A trait that is determined by a single gene
Complex trait
Traits that are determined by one or more genes and environmental factors.
Levels of genetics
DNA - genes - chromosomes - genomes - individuals - families - populations
Define: 9q21.11
9= chromosme, q=long arm, 21=region, 1= band, 1=subband
Genome annotation
The process of marking all the genes in a genome and ascribing functions to each
Locus
The site of a gene within the genome
Null mutation
Loss-of-function mutation which completely abolishes the activity of a gene
Genetic population
A large collection of alleles, distinguished by frequency/
Why is it important that cells divide
So that organisms can grow and replace dead cells
Cyclin proteins
Cells release cycins to tell other cells when to start or stop dividing. Triggered by cell geometry, contact with borders, or cellular concentrations.
G1 phase
Following mitosis, cells continue synthesizing proteins, lipids, and carbs.
DNA damage checkpoint
During S phase, the cell cycle will pause while proteins will repair the damaged DNA
Apoptosis checkpoint
Before mitosis, if there is not enough survivin protein accumulation, the cells will die
Telomeres
Chromosome tips which shorten to tell a cell how many cell divisions remain within the lifetime. Telomerase preserves the length of telomeres in gametes and cancer cells.
G2 phase
The mitotic machinery is incorporated into the cell. This includes: centromeres, centrioles, microtubule assembly, and the mitotic spindle.
How do chromosomes move during anaphase?
The enzymatic degradation of cohesin, the protein that links sister chromatids together, coupled with changes in microtubule length.
Propidium iodide staining
Stains chromosomes to identify the stage of the cell cycle. The intensity of the staining is proportional to the amount of DNA (ploidy)
Endoreduplicaiton
Increase in cell size without cytokinesis. Endocycled cells proceed directly from G2 to G1 and endomitotic cells go through mitosis but never undergo cytokinesis.
2 Major goals of meiosis
Reduce the number of chromosomes by half and to introduce diversity of DNA into the population
Meiosis 1
REDUCTIVE DIVISION - 2n to n
Meiosis II
EQUATIONAL DIVISION - goes from 2 cells to 4
Crossing over
ONLY occur in Prophase 1 during homolog pairing
Prophase I phases
Lengthy zooms produces drowsy dudes
Leptotene Zygotene Pachytene Diplotene and Diakinesis
*crossing over occurs in the middle
Mendelian trait
A trait controlled by a single locus/gene
Elmenten
Mendel’s word for hereditary material (i.e: DNA/genes)
Law of segregation
Alleles for each gene segregate randomly during Meiosis
Compound heterozygotes
Different mutant allele combinations due to many variants of a gene
Epistasis
One gene affects the expression of a second gene (ex: bombay h protein)
Penetrance Vs. Expressivity
Penetrance = whether or not the phenotype emerges with corresponding genotypes
Expressivity = the varying degrees of phenotype severity
Pleiotropy
One gene has several functions and therefore one mutation can have several different phenotypic effects
Phenocopy
Trait that appears inherited but is caused by the environment
Genetic heterogeneity
Different genes can produce identical phenotype
Pseudoautosomal regions
X and Y chromosome regions with genes that require 2 copies (alleles) and are found on both types of chromosomes. At the point of crossing over
Why are Y-linked traits rare?
Because there are very few total genes on the Y chromosome
Fun facts about mitochondrial DNA
Has a high mutation rate, circular, and high exposure to free radicals
X-inactivation
Balances the inequality of X gene expression in females
Lyon hypothesis
X-inactivation happens randomly during prenatal development, so you have random tissue regions with maternal X and those with paternal X. Creating mosaic
Genomic imprinting
Autosomal gene expression that is dependent upon the parent that the alleles are inherited from.
Uniparental Disomy
Rare inheritance of two chromosomes from the same parent. Due to nondisjunction in the same chromosome or trisomy followed by chromosome loss
Cytogenics
The study of chromosomal structure
During what phase are chromosomes the most condensed?
Mitotic metaphase
Kinetochore
Mediates the attachment of spindle apparatus during chromosome migration
Ideograms
Black and white diagrams of a chromosome with G bands
FISH
DNA probes labeled with fluorescent dye. Helps to distinguish individual chromosomes and individual genes. Can tell you the number of chromosomes
What does this represent: t(7;9)(p21.1;q34.1)
A translocation from chromosome 7 to chromosome 9
Chromothripsis
One or more chromosomes shatter - often results in loss of function
Causes of polyploidy abnormality
Multiple fertilizations or diploid gamete
Reciprocal translocation
Nonhomologous chromosomes exchange segments and have a normal amount of genetic material (often aphenotypical)
Robertsonian translocation
Nonhomologous acrocentric chromosomes break at the centromere so the two arms fuse together and create one large chromosome
Isochromosomes
Centromeres divide along the incorrect plane, so there are duplicate arms on the same chromosome
Ring chromosomes
Telomeres are lost and the sticky ends fuse together into a ring
Cri-du-chat
Caused by 5p arm deletion
Down syndrome
Trisomy 21
Edwards syndrome
Trisomy 18
Patau syndrome
Trisomy 13
Turner Syndrome
single X females
Klinefelter Syndrome
XXY males
Jacobs Syndrome
XYY males, most have normal phenotype
XXYY syndrome
Severe behavioral problems, infertility, treated with testosterone
Copy number variant
Deletion or duplicaiton of a 1 Kb+ DNA segment
Charcot-Marie-Tooth
Motor and sensory neuropathy diseases caused by CNV
Comparative Genomic Hybridization (CGH)
Staining technique for gene regions. Tells you how many copies of the gene you have for each chromosome pair
Mutational hot spots
Locations on genes where mutations are likely to occur. Typically on non-canonical DNA structures, such as palindromes and inverted repeats
Transition substitution
Purine is changed to another purine or pyrimidine to pyrimidine
Transversion substitution
Purine replaces pyrimidine or vice versa
Phenylketonuria (PKU)
New drugs called PALYNZIQ is modified phenylalanine lyase, preventing build-up
Spinal muscular atrophy (SMA)
Splicing out of exon 7 can be fixed with antisense oligonucleotides or exogenous delivery of the SMN protein
Heteroplasmy
The presence of multiple mitochondrial DNA types distributed randomly into daughter cells
