Chapters 5-6: Genetics and Genetic Disorders Flashcards
What are the three main components of a nucleotide in DNA?
Deoxyribose sugar, phosphate group, and one of four nucleobases (adenine, cytosine, guanine, or thymine)
AT: GC
Briefly go over DNA replication
DNA helicases unwind and separate DNA strands
Primase instills RNA primers which indicate the starting point
DNA polymerase binds to single DNA strand, matches appropriate base to template base
Reads up (3’ to 5’) -> Writes down (5’ to 3’)
Ligase binds Okasaki fragments on the lagging strand
What is the difference between the leading and lagging strand during DNA replication?
The leading strand is synthesized continuously in the 5’ to 3’ direction
Lagging strand is synthesized in short fragments (Okazaki fragments), later joined by DNA ligase
Approximately what percentage of the human DNA chromosomes code for proteins?
- 10%
- 1%
- 80%
- 50%
1%
The primary role of genes is to
- Code for reproduction
- Direct the synthesis of proteins
- Determine cellular apoptosis
- Determine differentiation
Direct the synthesis of proteins
What is the difference beween DNA and RNA?
DNA contains deoxyribose and uses thymine as a base
RNA contains ribose and uses uracil instead of thymine
* A-U
What are the main types of RNA and their role in protein synthesis?
mRNA (messenger RNA): carries genetic instructions from DNA
rRNA (ribosomal RNA): part of the ribosome structure
tRNA (transfer RNA): delivers amino acids during translation
What is a codon and what does it do?
A codon is a sequence of three nucleotides in mRNA that specifies a particular amino acid during protein synthesis
What are introns and exons?
Introns are non-coding regions of a gene that are removed from the pre-mRNA
Exons are coding regions that remain and are spliced together to form mature mRNA
What is the difference between transcriptional activators and repressors?
Activators are proteins that enhance transcription by assisting RNA polymerase binding
Repressors inhibit transcription by blocking RNA polymerase
How is a protein formed from DNA?
Simple steps
Transcription of DNA forms RNA -> translated to create an amino acid chain -> folding occurs to create a protein
What are the four major tissue categories?
Epithelium
Connective tissue
Muscle
Nerve
Where are epithelial tissue found?
Line the glands, blood vessels, and internal surfaces
What is the function of connective tissue?
Functions as a “scaffold;” plays an important part in the support and repair of nearly every tissue and organ
What are the different layers of epithelial tissue?
Simple: one layer
Stratified: many layers
Pseudostratified: one layer but appears as many layers
What are the different types of muscle tissue and where are they found?
Skeletal muscle: striated, tubular, multi-nucleated; voluntary, usually attached to skeleton
Smooth muscle: non-striated, spindle-shaped, uni-nucleated; involuntary, covers wall of internal organs and found on blood vessels
Cardiac muscle: striated, branched, and uni-nucleated; involuntary, only covers walls of the heart
What is a chromatid?
Two identical linear chromosome units which separate during meiosis
What are the sex chromosomes compared to the remaining chromosomes?
22 autosomes (homologous)
Female: 2 X-chromosomes
Male: 1 X and 1 Y chromosome
What are alleles?
Two alleles for each gene, one from each parent
Homozygous: both alleles are functionally identical
Heterozygous: two different alleles
Aneuploidy
Aberrant number of chromosomes
What are some examples of autosomal chromosome disorders?
- Trisomy 21 (Down syndrome)
- Trisomy 18 (Edwards syndrome)
- Trisomy 13 (Patau syndrome)
- Cri du Chat syndrome
What is Down syndrome and what are causes, signs and symptoms, and testing involved?
Trisomy 21 with physical and mental disorders
Causes:
* Non-disjunction (95%)
* Risk increases with increased maternal age
Signs and symptoms
* Simian crease, heart defects, leukemia, dementia, decreased IQ and speech difficulties
Testing
* Prenatal: US or amniocentesis
* Karyotype test
What is Klinefelter syndrome and what are causes, signs and symptoms, and testing involved?
Sex chromosome disorder - XXY
Males with an extra X chromosome
Signs and symptoms:
* Both male and femal sexual characteristics
* Decreased testosterone, gynecomastia, weak muscles and bones
Testing:
* Clinical exam, typically detected during puberty
* Chromosomal testing
* Hormones
Treatment:
* TRT
* Language therapy
