Term 2 Genetics Flashcards
What role does DNA plays in inheritance
DNA carries genetic information - the genetic code. The basis for this lies in the fact that DNA makes genes and genes make chromosomes.
Describe the relationship between DNA, genes, chromosomes
Chromosomes carry DNA in cells. DNA is responsible for building and maintaining your human structure. Genes are segments of your DNA, which give you physical characteristics that make you unique.
Describe how both genetic and environmental factors determine phenotypes
Environmental factors such as diet, temperature, oxygen levels, humidity, light cycles, and the presence of mutagens can all impact which of an animal’s genes are expressed, which ultimately affects the animal’s phenotype.
What is a karyotype
A karyotype is an individual’s complete set of chromosomes. The term also refers to a laboratory-produced image of a person’s chromosomes isolated from an individual cell and arranged in numerical order.
Recall the sex chromosomes for humans, and describe how these determine gender
Sex chromosomes in humans consist of two types: X and Y chromosomes. Females typically have two X chromosomes (XX), while males have one X and one Y chromosome (XY).
Explain how the structure of DNA relates to its function
DNA’s double helix structure, with complementary base pairing (A-T, C-G), ensures stability, accurate replication, and accessibility for protein synthesis. Its sequence encodes genetic information, dictating traits and cellular functions.
Describe the structure of DNA
Double helix formed by two antiparallel strands of nucleotides.
Each nucleotide consists of a phosphate group, a deoxyribose sugar, and one of four nitrogenous bases: adenine, thymine, cytosine, or guanine.
What is Chargaff’s rule
Chargaff’s Rule states that adenine(A) pairs with thymine (T), and cytosine (C) pairs with guanine (G), ensuring complementary base pairing.
Describe the relationship between DNA, genes and proteins
Genes are a region of DNA that act as instructions to create molecules called proteins.
Describe the process of gene synthesis in regard to translation
Translation:
Occurs in the cytoplasm
mRNA is translated into a protein with the help of ribosomes and transfer RNA (tRNA)
tRNA delivers amino acids to the ribosome according to the mRNA codons
Ribosomes catalyze the formation of peptide bonds between amino acids to form a polypeptide chain
Compare DNA and RNA
DNA:
Double-stranded
Sugar is deoxyribose
Bases include adenine (A), thymine (T), cytosine (C), and guanine (G)
Stable structure, less prone to degradation
Stores genetic information
RNA:
Single-stranded
Sugar is ribose
Bases include adenine (A), uracil (U), cytosine (C), and guanine (G)
Less stable, more prone to degradation
Involved in various cellular processes such as protein synthesis, gene regulation, and cell signaling
Describe the process of gene synthesis in regard to transcription
Gene synthesis involves two main processes:
Transcription:
Occurs in the nucleus
DNA is transcribed into mRNA by RNA polymerase
mRNA carries the genetic code from the DNA to the ribosome
Describe the process of mitosis
Type of cell division in somatic cells
Produces two identical daughter cells
One round of division (PMAT):
Prophase – the cell (P)repares for division: the chromosomes condense and the nucleus starts to break down
Metaphase – the chromosomes line up along the (M)iddle of the cell
Anaphase – the chromosomes separate and are dragged (A)way from each other
Telophase – (T)wo nuclei form, each with its own set of identical DNA
Results in diploid daughter cells (2n)
Occurs in growth, repair, and asexual reproduction
Describe the process of Meiosis
Type of cell division in germ cells
Produces four non-identical daughter cells
Two rounds of division (PMAT I and PMAT II)
Results in haploid daughter cells (n)
Occurs in the formation of gametes (sperm and egg) for sexual reproduction
Describe a Gene
Genes are made up of sequences of DNA and are arranged, one after another, at specific locations on chromosomes in the nucleus of cells that contain instructions for specific traits.
They determine the expression of a particular characteristic.
Genes can have multiple alleles.
They are located on chromosomes within the cell nucleus.
Mutations in genes can lead to variations in traits.
Describe an Allele
Alleles are different forms of a gene.
They occupy the same position (locus) on homologous chromosomes.
Alleles can be dominant or recessive.
Individuals inherit one allele from each parent, resulting in a genotype.
What was Mendel’s contributions to the study of genetics
Gregor Mendel is often referred to as the “Father of Genetics” for his groundbreaking work on the inheritance of traits.
He conducted experiments on pea plants in the mid-19th century and formulated the fundamental principles of inheritance, which laid the foundation for modern genetics.
Why did Gregor Mendel choose pea plants
Variability: Pea plants exhibit a wide range of easily observable traits, such as flower color, seed shape, and plant height.
Controlled Breeding: Pea plants can self-fertilize or cross-fertilize, depending on the experimental design. Mendel could control the breeding process by manually pollinating specific plants, ensuring accurate records of parentage and offspring.
Short Generation Time: Pea plants have a relatively short life cycle, allowing for multiple generations to be studied within a reasonable timeframe.
Large Number of Offspring: Pea plants produce a large number of seeds per pod, providing ample material for statistical analysis
Ease of Cultivation: Pea plants are easy to cultivate and maintain in a controlled environment, making them ideal for experimental purposes.
Describe some examples of human genetic traits
Eye colour, hair colour / texture, blood type, freckles, height, fingerprint
Explain how mutations can occur
Spontaneous Mutations: Arise naturally during DNA replication, repair, or recombination due to errors by DNA polymerases or chemical changes in DNA bases.
Environmental Factors: Exposure to radiation, chemicals (mutagens), or biological agents can damage DNA, leading to mutations.
Mutagenic Chemicals: Directly interact with DNA, causing changes in its structure. Examples include alkylating agents and intercalating agents.
Transposons: DNA sequences that can move within the genome, disrupting genes or regulatory sequences when they insert into new locations.
DNA Replication Errors: Mistakes during DNA replication, such as incorrect nucleotide insertion, deletion, or skipping, can lead to mutations.
Errors in DNA Repair: Mistakes in DNA repair mechanisms can result in mutations if damage is not properly repaired or if repair enzymes introduce errors.
Describe three different types of mutation
Point Mutation:
Involves changes to a single nucleotide base.
Subtypes: Substitution (base replaced), Insertion (base added), Deletion (base removed).
Frameshift Mutation:
Results from addition or deletion of nucleotides, shifting the reading frame.
Causes significant changes in amino acid sequence during translation.
Chromosomal Mutation:
Alters chromosome structure or number.
Examples: Duplication (segment copied), Deletion (segment lost), Inversion (segment reversed), Translocation (segment moved to another chromosome).
Order the parts of a cell from biggest to smallest e.g cell to chromosome
Cell, Nucleus, Chromosome, Gene, DNA
Explain how mutations can affect the chance of an organism’s survival (negative and positive)
Negative Effects:
Lethal Mutations: Cause death before or shortly after birth.
Deleterious Mutations: Harmful changes to proteins or regulatory sequences.
Reduced Fitness: Decrease in ability to compete, evade predators, or resist diseases.
Positive Effects:
Beneficial Adaptations: Provide advantages in specific environments.
Genetic Diversity: Contribute to adaptation to changing environments.
Evolutionary Innovation: Generate new traits or functionalities, driving diversification.
What are the sides of the DNA strand called
Phosphate backboard
What is a peptide bond
a chemical bond formed between two molecules when the carboxyl group of one molecule reacts with the amino group of the other molecule
explain the order of mRNA, tRNA, and rRNA and it’s function
mRNA (Messenger RNA) : It carries the instructions for making proteins from the DNA to the ribosomes.
tRNA (Transfer RNA) : It brings the building blocks (amino acids) to the ribosomes based on the instructions from mRNA.
rRNA (ribosomal RNA) : It helps in the assembly of amino acids into proteins at the ribosomes.
What is the interphase
Interphase is the preparatory phase of the cell cycle where cells grow, perform their regular functions, and replicate their DNA in three stages: G1, S, and G2. It’s a vital period for the cell’s growth, maintenance, and readiness for division. occurs before miosis and mitosis
parts of a chromosome
The significant parts of a chromosome are the centromere, telomeres, and chromatids.
What does it mean if a chromosome is homologous
Homologous chromosomes are pairs of chromosomes in a diploid organism that have similar genes, although not necessarily identical.
When does crossing over occur in meiosis
Crossing over, also known as genetic recombination, occurs during prophase I of meiosis. This is when homologous chromosomes pair up and exchange segments of their DNA, leading to the reshuffling of genetic material.
