Lecture 3 Flashcards
What are non-germinal cells?
Diploid (46 chromosomes, paired)
Germinal cells
Haploid (Sperm/ovum cells, 23 chromosomes, no pairs)
Aneuploidy
Extra/missing chromosomes (ex. down syndrome an extra chromosome creating the 21st trisomy)
Phenotype
Expressed traits derived from genotype
Genotype
The genetic constitution of an individual organism
In what state(s) is the dominant gene expressed?
Homozygous or heterozygous state
In what state(s) is the recessive gene expressed?
Homozygous only
Codominant gene
Both alleles of a pair are expressed (creates a ‘mix’ therefore, both genes are expressed)
Sex-linked gene
Genes carried on sex chromosomes produced sex-linked traits (X or Y)
Epigenetics
How behaviours and environments can change gene expression (activate, amplify, repress gene expression, increase risk of disease)
What are factors that can affect epigenetics
Diet, obesity, physical activity, smoking, alcohol consumption, environmental pollutants, psychological stress, depression, shift work,
X inactivation/Lyonization
Only one of the two X chromosomes in females is genetically active (lost later in cell development)
Barr body/sex chromatin body
Inactive X chromosome
Karyotype
Chromosomes analysis to study the composition and abnormalities in chromosomes by their number and structure.
Chromosomes
Double coils of DNA combined with proteins which exist in pairs (23 pairs in humans, 22 autosomes and 1 sex chromosomes)
Nucleotide
The basic structural unit of DNA, that form nitrogen-containing bases(C, G, A, T)
Purines
Adenine, Guanine
Pyrimidine
Thymine, Cytosine
Replication of DNA
The original chain is used as a template for the synthesis of the new chain; forms 2 double strands (new strand + old strand)
How was DNA replicated?
Semi-conservative replication (chains separate and act as templates for copies to form 2 new identical strands of DNA)
DNA to protein cycle
Transcription of DNA to mRNA in the nucleus. mRNA is processed by removing the non-coding (introns) and splicing coding regions (exons). In the ER the mRNA undergoes translation for protein formation in ribosomes by rRNA. tRNA transfers anticodons to the mRNA Codons to produce proteins.
True or False: Mitochondria has its own DNA?
True, small amounts of circular DNA (some code of ATP-generating enzymes)
True or False: Sperm has more mitochondria than human ova?
False, human ova has serval mitochondria whereas sperm contain very few (most mitochondrial disease come from the ova, only inherit mitochondrial DNA from mothers)
Symptoms of mitochondrial disease
Poor growth, Muscle weakness, low muscle tone, vision and/or hearing problems, learning disabilities, delays in development, autism-like features, heart or liver diseases
What cells use Mitosis as a method of cell division?
Somatic cells (cardiac, skeletal, nerve, connective tissue, liver, blood-forming cells)
What cells use Meiosis as a method of cell division?
Germ cells (genetic material to be sex cells)
Which mature cells cannot divide and reform
Cardiac, skeletal muscle, and nerve cells
Sequence of mitosis
Prophase, Metaphase, Anaphase, Telophase
Sequence of meiosis
The first meiotic division reduces the number of chromosomes by half (daughter cells only receive only half of the chromosomes from parent cells). The second meiotic division is similar to mitosis but each cell only contains 23 chromosomes
Gametogenesis
Forming gametes (mature germ cells)
Gonads
Testes and ovaries; capable of developing into mature sperm or ova
Spermatogenesis
Development of sperm (starting with 46 chromosomes and dividing into 23 chromosomes to form 4 sperm per one precursor cell)
Spermatogonia
Precursor cells in the testicular tubes
Oogenesis
Development of ova (one ovum formed per one precursor cell, the rest are polar bodies)
Oogoina
Precursor cells in a female fetus
Monosomy
Absence of a chromosome in a cell
Trisomy
Presence of an extra chromosome in a cell
Deletion
Chromosome breaks during meiosis and the broken pieces are lost
Translocation
Misplaced chromosome, or part of it, attaches to another chromosome (can cause miscarriage)
Nondisjunction in Meiosis
Having a missing or extra pair of chromosomes in the first or second meiotic division
Turner Syndrome
One X chromosome; sterile
Triple X Syndrome
Three X chromosomes; 2 Barr bodies; fertile
Klinefelter Syndrome
Two X and one Y chromosomes; male; 1 Barr body and Y fluorescent body; sterile
XYY Syndrome
One X and two Y; 2 Y Fluorescent bodies; fertile
Fragile X syndrome
An abnormal X chromosome near its tip, causes mental deficiency, high number of CGG sequences in DNA chains; passed on by mothers to their daughters and sons and by fathers to their daughters
Down Syndrome
Trisomy of chromosome 21 by nondisjunction or translocation; developmental disabilities, cardiac malformation, major defects in other organ systems; mostly seen in births by older women
Mutation
Permanent change in genetic material that may occur spontaneously or after exposure of a cell to radiation, chemicals, or viruses
Single nucleotide polymorphisms (SNPs)
The most common type of genetic variation among people. SNP represents a difference in a nucleotide. ex. It may replace a nucleotide cytosine with thymine (How people can react differently to the same things, ex. some people can metabolize alcohol better than others)
Recombinant DNA technology
Joining together of DNA molecules from two different species to produce a new genetic combination (removal or addition of gene)
Gene therapy
Using genes to treat or prevent disease (cells are removed, treated, and reinfused) . In the future genes can be inserted into the patient’s cells for treatment
Bioinformatics
Improved sequencing technologies and a better understanding of genes. Allows sequencing of the human genome in a matter of days for hundreds of dollars
Personalized therapy
Using genetic code to create treatments for illnesses to specifically/uniquely treat that person.
Eugenics
The study of how to arrange reproduction to allow the increase of favourable traits expressed in the human population
