Grade 12 Life Sciences - DNA, Genetics & Genetic Engineering Flashcards

Flashcards covering key vocabulary and concepts related to DNA, genetics, and genetic engineering for Grade 12 Life Sciences.

Erwin Chargaff's Research (1949)

The ratios of adenine (A) to thymine (T) and guanine (G) to cytosine (C) are equal in all organisms, indicating chemical pairings between these bases. Also, the amounts of A, T, C, and G vary by species, indicating that DNA, not protein, might be the genetic material of life.

Rosalind Franklin's Contribution (1952)

Used X-ray diffraction to create Photo 51, demonstrating the double-helix structure of deoxyribonucleic acid.

Watson and Crick's Model (1953)

Formulated an accurate description of DNA's complex, double-helical structure, based on Photo 51 and Chargaff’s rule. They determined that the strands are antiparallel, composed of nucleotides connected with covalent bonds, and that the two strands are connected with weak, hydrogen bonds.

Nucleic Acids

Large molecules that store genetic information (the code) that controls cellular activity and an organism's development, controlling protein synthesis.

DNA (Deoxyribonucleic Acid)

An organic compound with a unique molecular structure that can be thought of as a twisted ladder (double helix). It contains the genetic code and is organized into chromosomes located in the nucleus.

Nucleotide

The monomer of a nucleic acid, consisting of a sugar, a phosphate group, and a nitrogenous base.

Nitrogenous Bases in DNA

Adenine (A), Thymine (T), Guanine (G), and Cytosine (C)

Complementary Base Pairing

A with T (2 hydrogen bonds), and C with G (3 hydrogen bonds)

Importance of DNA

Carries the coded genetic information in each cell, can replicate, indirectly supervises protein manufacture, and controls cell activities.

RNA (Ribonucleic Acid)

Single-stranded, involved in protein synthesis, has ribose sugar, and contains uracil instead of thymine.

Types of RNA

mRNA (messenger RNA), tRNA (transfer RNA), and rRNA (ribosomal RNA)

Function of RNA

Carries instructions from DNA to ribosomes, controlling the synthesis of proteins by assembling amino acids in the correct sequence.

Mitochondrial DNA (mtDNA)

A small, circular piece of DNA found in the matrix of the mitochondrion; it contains the code for the enzymes that control respiration and is inherited maternally.

Endosymbiosis

Theory that mitochondria originated as bacteria that invaded an ancestral eukaryote and developed a symbiotic relationship.

Protein Synthesis

The process of making a chain of amino acids that forms a functional protein, using instructions from the DNA code.

Processes in Protein Synthesis

Transcription (making mRNA from DNA) and Translation (decoding mRNA to assemble amino acids).

Transcription

Making mRNA molecules from DNA; occurs in the nucleus with the help of RNA polymerase.

Translation

Decoding the mRNA and assembling amino acids in the correct order to form a polypeptide; occurs at a ribosome, involving tRNA and codons/anticodons.

Mutation

A random change in the DNA sequence that can affect the protein coded for by the DNA sequence.

Point Mutation

Involves a single base change to the DNA sequence, like substitution, insertion, or deletion.

Frameshift Mutation

Addition or deletion of a nucleotide base, changing the length of the reading frame and potentially altering protein function.

Mutagens

Factors that can cause mutations in DNA, such as UV light, X-ray radiation, mutagenic chemicals, viruses, and microorganisms.

Effects of Mutations

Lethal (harmful, causing death), Neutral (no effect on phenotype), and Beneficial (improving survival chances).

DNA Profiling (DNA Fingerprinting)

Process where a specific DNA pattern (profile) is obtained from a person or sample of bodily tissue, using highly variable, non-coding DNA regions (microsatellites or STRs).

Uses of DNA Profiling

Forensics, paternity testing, identifying casualties, diagnosing inherited disorders, fighting illegal trade, establishing family relations, and matching tissues for organ transplants.

Polymerase Chain Reaction (PCR)

A technique used to amplify (make more copies) small amounts of DNA for extensive analysis.

Chromosomes

Structures made of DNA and proteins (histones) that carry genetic information; they are organized from wound DNA.

Karyotype

A linear arrangement of chromosomes from a cell, arranged from largest to smallest. Somatic cells are diploid (2n), and gametes are haploid (n).

Meiosis

Cell division in reproductive organs to produce gametes with half the number of chromosomes as the parent cell.

Stages of Meiosis

Meiosis 1 (reductive division) and Meiosis 2 (copying or mitotic division).

Crossing Over

The exchange of genetic material between two homologous chromosomes, resulting in recombination of genes; occurs during Prophase 1 of meiosis.

Chromatid

A chromatid refers to either of the two identical copies formed by the replication of a single chromosome.

Bivalent

A bivalent (also referred to as a tetrad) is the association of a pair of homologous chromosomes that physically held together by at least one DNA crossover. This occurs during prophase 1 of meiosis.

Non-disjunction

Failure of homologous chromosomes to segregate properly during Anaphase 1 or 2.

Down Syndrome

Condition caused by an extra copy of chromosome 21 (trisomy 21), leading to altered development and associated characteristics.

Gene Mutations

Random changes in DNA (insertions, deletions, substitutions) that cause variations in genes.

Crossing Over

Swapping of sections of chromosomes in a bivalent during prophase I

Independent/Random Assortment

Homologous pairs of chromosomes line up on the equator; material and paternal versions can be mixed up in the final gametes

Random Fertilization

The traits each gamete has cause every zygote to be unique since any of the numerous male gametes can fertilize any of the female gametes

Genetics

The passing of information from one generation to another, and variation

Gregor Mendel

Founder of genetics; used pea plants as model system to study and create genetics laws

Locus

The location of a gene on chromosome

Genotype

Genetic make-up of a trait

Phenotype

Outward expression (observable characteristic) of the genes

Human Genome Project (HGP)

Identifying all the genes in human DNA, determining the sequences of base pairs, storing information, and improve tools for data analysis

Genetic Diagram

Representation to show how characteristics are inherited by the next generation

Complete Dominance

Allele that is fully expressed in the phenotype of a heterozygous organism

Mendel's Law of Segregation

During meiosis, allele pairs segregate so that the gametes have a single allele for each characteristic

Mendel's Law of Dominance

If two alleles at a locus differ, then the dominant allele determines the organism’s appearance

Mendel's Law of Independent Assortment

The alleles of different genes segregate randomly and independently of one another during gamete formation

Pedigree Charts (Family Trees)

Shows the genotypes and phenotypes of several generations of individuals in a family to predict whether a couple is likely to pass on a genetic disorder/traits

Genetic Counselor

Medical professional trained to use family history to predict the likelihood of traits in future generation and guide prospective parents.

Switched on Genes

Genes that are being expressed/ making proteins

Gonosomes

Gonosomes, or sex chromosomes, are the pair of chromosomes for sex determination

Autosomes

Chromosomes that are not involved in sex determination (non sex chromosomes)

Sex Determining Chromosomes - Humans

In humans and most animals the gonosomes are designated X and Y. The gonosomes in females include two X chromosomes (XX), while males have one X and one Y chromosome (XY).

Y Chromosome

The Y chromosome is very short and has few genes on it other than those responsible for maleness.

Sex-Linked Alleles/ X-Linked Genes

Alleles carried on the differential or non-homologous region of the gonosomes

Continuous Variation

Traits that show large number of intermediate forms and are usually controlled by a large number of alleles not necessarily operating in a strict dominance hierarchy

Polygenic Traits

Traits are determined by the combined effect of more than one pair of genes

Intermediate Expression

Expression when both alleles (which are different) of a gene at a locus are partially expressed and apparent blending can occur in the phenotype

Codominance

For some traits, two alleles can be codominant which is to say, both alleles are expressed in the phenotype of heterozygous individuals.

Pleiotropy

When a single gene is responsible for a variety of traits

Penetrance

The extent to which the genes affect the characteristic

Environment

Influence on variation where chemicals, nutrients, stress, education, disease, etc. can all influence the way genes manage to express themselves

Genetic Engineering

Manipulation of an organism’s genome using biotechnology to change the genetic makeup of cells, including the transfer of genes within and across species boundaries to produce improved or novel organisms.

Biotechnology

The use of biology (and biological processes) to develop new products, methods and organisms intended to improve human health and society

Recombinant DNA

DNA that is not in its original form- a sequence of DNA has been taken and combined with another sequence in a new way.

Genetically Modified Organism (GMO)

Organism whose genome has been modified

Bio-factories

Vector that delivers gene

Recombinant DNA Technology

Beneficial genes are introduced into an organism to create genetically modified organisms

Manufacture of Insulin (Recombinant DNA Technology)

Finding a desirable gene and moving into the cells of another organism using a vector (usually a plasmid)

Transformation of Plants to create GM Crops (Gene Gun Method)

Metal pellets are coated with the desirable DNA/gene of interest and are fired into plant cells

Transformation of Plants to create GM Crops (Recombinant DNA Technology)

The soil bacterium Agrobacterium tumefaciens is used to insert the gene of interest into plant cells

Transgenic Animals

Having an altered genome by the introduction of a gene (or genes) from another species

Sheep Dolly

Cloned animal

Importance of Transgenic Animals

To study diseases, for pharming, and for improving livestock

Gene Therapy

Genetic engineering technique that is used for correcting defective genes responsible for disease development

Somatic Cell Nuclear Transfer (SCNT)

Procedure used to clone animals by isolating and extracting somatic cell and inserting into enucleated egg cell and using electricity to fuse the new nucleus

Polyploidy

Genetic engineering that occurs at the chromosome level by inducing polyploidy in plants

CRISPR (Clustered Regularly Interspaced Short Palindromic Repeat)

Allows researchers to permanently modify genes and can be used in many applications

Artificial Selection (Selective Breeding)

Farmers chose cattle with beneficial traits such as larger body size or high milk production, and made the individuals with the trait breed

Hybrid Vigour

Increased function of any biological quality in a hybrid offspring due to offspring produced from dissimilar individuals (through sexual reproduction) who are genetically superior to their parents