Genetics Unit Test Bio Flashcards
Somatic Cells
These are all the cells in your body except sperm and egg cells. Examples include skin cells, liver cells, and brain cells. They are diploid (2n), meaning they carry two complete sets of chromosomes (one from each parent). Somatic cells undergo mitosis for growth and repair.
Gametic Cells (Gametes)
These are reproductive cells — sperm in males, and eggs in females. They are haploid (n), carrying only one set of chromosomes. When a sperm fertilizes an egg, the resulting zygote becomes diploid again.
Germ Cells
Found only in the reproductive organs (testes and ovaries), germ cells are diploid cells that divide via meiosis to create gametes. They act as the precursors to gametes
stem cells
Undifferentiated cells that have the potential to become many different types of specialized cells. They play a role in development and repair. Types include embryonic stem cells (pluripotent), adult stem cells (multipotent), and induced pluripotent stem cells (iPSCs), which are adult cells reprogrammed to act like embryonic ones.
Identify/illustrate the structure of a chromosome
A chromosome is a tightly packed bundle of DNA found in the nucleus of a cell. Each consists of:
Chromatids: When duplicated, chromosomes consist of two identical chromatids (sister chromatids) joined at a centromere.
Centromere: Region that joins sister chromatids.
Telomeres: Protective caps at each end of the chromosome that prevent DNA degradation.
DNA is wound around proteins called histones to form chromatin, which coils tightly into chromosomes during cell division.
purpose of mitosis
-Grow by increasing the number of cells.
-Repair damaged or old tissues.
-Replace dead cells.
it produces 2 genetically identical daughter cells
explain and illustrate the process of mitosis
Prophase:
Chromatin condenses into chromosomes, spindle fibers form, and the nuclear envelope begins to break down.
Metaphase:
Chromosomes align at the center of the cell (metaphase plate), attached to spindle fibers.
Anaphase:
Sister chromatids are pulled apart to opposite poles of the cell.
Telophase:
Nuclear envelopes reform around each set of chromosomes, which begin to uncoil.
Cytokinesis:
The cytoplasm divides, creating two identical daughter cells.
explain how cancer occurs
- Regulation of the cell cycle occurs through a complex network of signals in the cell. Something that interferes with these signals could result in uncontrolled growth.
- cancer is the result of uncontrolled, rapid cell division. Cancerous cells progress quickly from one cell division to the next, resulting in a mass of cells, called a tumour.
Explain the different types of stem cells, where they are found, why they are important, and ethical dilemmas
Stem cells are undifferentiated (unspecialized) cells that, under the
right conditions, can develop into any one of the more than 200 types of somatic cells.
Embryonic Stem Cells: Pluripotent
obtained from embryos
Adult Stem Cells: (totipotent)
somatic cells that have retained the ability to differeniate into other cell types.
induced pluripotent stem cells, which are specialized adult stem cells that have been induced to return to a stem-cell-like state
ethical dilemmas:
-destroying embryos for research
-concerns about “playing god” or designing babies
-risk of human cloning misuse
Explain and illustrate the process of meiosis and chromosome count at each stage
explain oogenesis
-
-occurs in females ovaries
-before brith; pauses at prophase 1 until puberty
-involves unequal cytoplasmic division
-results in 1 viable egg (from the larger cell) (ovum) and 3 polar bodies (non-functional)
-The egg contains nutrients to support the zygote.
-The smaller cell becomes the polar body and degenerates.
-Meiosis II is completed only after fertilization.
-A mature egg and another polar body are produced after meiosis II.
-The egg’s haploid nucleus fuses with the sperm’s haploid nucleus, forming a diploid zygote.
explain spermatogenesis
-occurs in testes, starts at puberty and continues throughout life
-a single germ undergoes meiosis to produce 4 equal-sized sperm cells
-the process is continuous and rapid
- Spermatogenesis starts with a diploid spermatogonium.
- At puberty, spermatogonia divide by mitosis, producing cells that undergo meiosis.
- Meiosis forms four haploid cells.
- After meiosis II, cells go through development to become mature sperm.
- The nucleus and essential molecules form the sperm’s “head.”
- The midsection contains mitochondria for energy.
- A tail (flagellum) develops for movement.
determine the haploid if given the diploid number
Just divide the diploid number by 2.
Example: If 2n = 46, then n = 23.
Haploid cells are gametes.
Identify scientists who discovered DNA structure
Watson and Crick: Proposed the double helix model.
Rosalind Franklin: Took X-ray images (Photo 51) that revealed DNA’s structure. cystalized something
Chargaff: Discovered base pairing rules (A=T, C=G).
compare DNA mutations
Deletions
Insertions
Inversions
Translocations
Define nitrogenous base, complementary base pair, sugar-phosphate backbone, histone, and nucleotide
Nitrogenous Base: Part of DNA; includes A, T, C, G.
Complementary Base Pair: A pairs with T, C with G via hydrogen bonds.
Sugar-Phosphate Backbone: Framework that supports DNA strands.
Histone: Protein DNA wraps around to form chromatin.
Nucleotide: Basic unit of DNA—sugar, phosphate, and base.
Where, when, and how genetic shuffling occurs in meiosis
When: Prophase I and Metaphase I.
Where: In germ cells undergoing meiosis.
How:
Crossing Over: Exchange of DNA between homologous chromosomes.
Independent Assortment: Random alignment of chromosomes.
Random Fertilization adds even more variation.
Read and analyze a karyotype
Trisomy (3 copies, e.g., Down syndrome - trisomy 21, trisomy 12-Klinefelter syndrome, trisomy 18- Edwards syndrome)
Monosomy (1 copy) (monosomy x- turner syndrome)
Sex chromosome anomalies (XXY, X0) (xxy- Klinefelter syndrome)
Define autosomal chromosome
Chromosomes 1–22 (not involved in determining sex).
Chromosomal mutations
Monosomy: One chromosome instead of two.
Trisomy: Extra chromosome.
Ex.
Trisomy 21: Down Syndrome.
Trisomy 18: Edwards Syndrome.
XXY: Klinefelter’s Syndrome.
tools used to detect genetic mutations
-karyotyping
-bloodwork (readings)
-dna sequencing
-genetic screening/panel testing
Difference in translocation in Meiosis I vs II
Meiosis I: both resulting cells are affected. Affects homolog pairing, can prevent separation.
Meiosis II: Affects chromatids, more subtle but still harmful. 2 of haploid cells are affected.
Artificial Insemination, IVF, Selective Breeding, Embryo Transfer
Artificial Insemination: sperm are collected and concentrated before being introduced into the female’s reproductive system
IVF: technique used to fertilize egg cells outside the female’s body
Selective Breeding: of breeding plants and animals for desirable traits
Embryo Transfer: an egg that has been fertilized artificially is transferred into a recipient female’s uterus.
Explain the difference between the law of segregation and the law of independent assortment. Can I illustrate the difference?
Law of Segregation (1st Law of Inheritance):
Each individual has two alleles for each gene (one from each parent).
During gamete formation, these alleles separate so that each gamete only gets one allele.
Illustration: In a monohybrid cross (Aa x Aa), the alleles A and a segregate during meiosis, and the offspring can inherit any combination (AA, Aa, or aa).
Law of Independent Assortment (2nd Law):
Genes on different chromosomes assort independently during gamete formation.
The inheritance of one gene does not affect the inheritance of another.
Illustration: In a dihybrid cross (RrYy x RrYy), alleles for R/r and Y/y separate independently, producing combinations like RY, Ry, rY, ry.
