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Questions and Answers
What biological process is covered in week 1 of the assignments?
What biological process is covered in week 1 of the assignments?
In which week are students expected to learn about DNA and RNA structure?
In which week are students expected to learn about DNA and RNA structure?
Which process is associated with the transformation of genetic information from DNA to RNA?
Which process is associated with the transformation of genetic information from DNA to RNA?
What is the final step in the flow of genetic information according to the assignment topics?
What is the final step in the flow of genetic information according to the assignment topics?
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What concept is introduced in week 3 of the assignments?
What concept is introduced in week 3 of the assignments?
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Which of the following processes directly involves the synthesis of proteins?
Which of the following processes directly involves the synthesis of proteins?
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Which of these processes is primarily responsible for copying genetic material?
Which of these processes is primarily responsible for copying genetic material?
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What is the primary function of transcription in cellular processes?
What is the primary function of transcription in cellular processes?
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Which week of the assignments is focused on the structure and types of nucleic acids?
Which week of the assignments is focused on the structure and types of nucleic acids?
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Which biological process involves the division of a cell's nucleus?
Which biological process involves the division of a cell's nucleus?
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Study Notes
Course Information
- Course: PTH241 Introduction to Human Genetics
- Instructor: Hanan H. Fouad
- Professor of Medical Biochemistry & Molecular Biology
- Faculty of Physical Therapy, Galala University
- Fall 2024
Intended Learning Outcomes
- Define genetics and understand its applications
- Comprehend the central dogma of molecular biology
- Identify the differences between genes, genome, and chromosomes
- Describe the number, structure, and classification of human chromosomes
- Distinguish crucial scientific terms in genetics
- Explain phases and checkpoints of the cell cycle
Genetics
- Definition: The study of genes, genetic variations, and heredity in organisms.
- Applications: Useful in studying hereditary diseases, cancer, bacteria, viruses, and forensic medicine. Used to produce large quantities of organic molecules (e.g., hormones, antibodies, antibiotics, vaccines) and is important in personalized medicine.
Important Scientific Terms
- Chromosome: Thread-like structure of DNA carrying genetic information.
- Gene: Specific length of DNA with a specific sequence of nucleotides located at a specific locus on a chromosome, and codes for the synthesis of a specific protein.
- Genome: The entire length of the nuclear DNA of an organism.
- Allele: A variety of the same gene with different nucleotide sequences located at the same locus.
- Dominant alleles: Always expressed in phenotypes.
- Recessive alleles: Expressed only when dominant alleles aren't present.
- Homozygous: Having two identical alleles for a gene.
- Heterozygous: Having two different alleles for a gene.
Genotype vs Phenotype
- Genotype: The genetic constitution of an organism (e.g., AA, Aa, aa), inherited to offspring.
- Phenotype: Observable characteristics (traits) of an organism resulting from interactions between genes and the environment, not inherited to offspring.
Gene Expression
- Central dogma of molecular biology: DNA to RNA to protein.
- Describes the flow of genetic information from DNA to RNA to proteins.
- Proteins carry out all biological or pathological functions of organisms.
Diploid vs Haploid Cells
- Somatic cells: Diploid (2n), containing 23 pairs of chromosomes (22 autosomal, 1 pair of sex chromosomes). Two sets of chromosomes.
- Germ cells (gametes, ovum & sperm): Haploid (1n), containing 22 autosomal chromosomes and one sex chromosome. One set of chromosomes.
Homologous Chromosomes
- A pair of chromosomes - one from each parent.
- Same length, position of the centromere, and the same genes at the same loci.
- Can be genetically different due to different alleles, especially in sex chromosomes (X and Y).
Types of Chromosomes
- Single chromosomes (s-chromosomes): Made from a single DNA molecule.
- Double chromosomes (d-chromosomes): Formed during DNA replication; each chromosome contains two chromatids linked at the centromere.
- Classification by centromere position: Metacentric (middle), submetacentric (slightly off-center), acrocentric (far off-center), and telocentric (at the end).
- Autosomal chromosomes: Paired and carry genes for somatic (body-related) characteristics.
- Sex chromosomes: Differ between male and female, and carry genes for sex characteristics.
Karyotyping
- Karyotype: A laboratory image of an individual's complete set of chromosomes arranged numerically.
- Can be used to look for abnormalities in chromosome number or structure.
- In females, one X chromosome is heterochromatic (Barr body), found attached to the nucleus, and regulates the amount of X-linked gene products.
Human Chromosome Nomenclature
- X-chromosome example: Short and long arms subdivided into regions and bands.
Numbering system of G bands in human chromosomes
- A system for labeling and ordering the chromosome bands
Telomeres
- Repetitive DNA sequences (TTAGGG) at the ends of linear chromosomes.
- Protect ends of chromosomes from damage and fusion with other chromosomes.
- Form 'capped' ends with specialized proteins.
- Prevents genomic instability, cell death or cancer.
Importance of Telomeres
- Prevent chromosome ends from being ligated together.
- Prevent ends from attack by exonucleases.
- Allow repair systems to distinguish true from broken ends.
- Compensate for incomplete replication of linear chromosome ends.
The End Replication Problem
- Telomeres shorten with each cell division.
- Beyond a critical length, cells stop dividing (senescence).
- Telomerase maintains telomeric length in some cells (e.g., germ line, stem cells, cancer cells)
Telomerase enzyme
- An enzyme that maintains telomeric length by extending the 3' end of the lagging strand template.
The Cell Cycle
- The sequence of growth and division of a cell.
- Interphase (G1, S, G2): The cell grows, copies DNA/organelles, and prepares for division.
- Mitosis (Prophase, Metaphase, Anaphase, Telophase): The cell divides.
- Go: A resting phase where cells are not preparing to divide.
- Checkpoints: Control points in the cell cycle to ensure DNA integrity before progression to the next phase.
Assignments
- Mitosis (week 1)
- DNA, RNA structure, types (week 2)
- Replication (week 3)
- Transcription (week 4)
- Translation (week 5)
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Description
Test your knowledge in the fundamentals of human genetics including the central dogma of molecular biology, gene classification, and cell cycle phases. This quiz will challenge your understanding of crucial genetic terms and their applications in areas such as hereditary diseases and personalized medicine.
