Bio Chem 1.3 Genetic Variation and Genetics Practice

Flashcards covering key concepts from Bio Chem 1.3 lecture notes including genetic variation, cell structures, DNA replication, mitosis, meiosis, mutations, and inheritance.

What is a cell?

The smallest unit of life that makes up all living things, carrying out essential functions to keep an organism alive.

What is the function of the nucleus in a cell?

It acts as the "brain" of a cell.

How many chromosomes are present in human somatic (body) cells versus gametic (sex) cells?

Human somatic cells contain 23 pairs (46 total) of homologous chromosomes, while gametic cells contain 23 chromosomes.

What does DNA stand for, and what is its shape?

DNA stands for Deoxyribo Nucleic Acid and has a Double Helix Shape (twisted ladder).

What are the three components that make up a nucleotide?

A Phosphate, Sugar, and a Base.

What is the Base Pairing Rule in DNA?

Adenine ALWAYS pairs with Thymine, and Cytosine ALWAYS pairs with Guanine.

What is a gene?

A section of DNA which carries instructions to make certain proteins that dictate the appearance of physical traits.

What are alleles?

Genetic variants that are different versions of the same gene and influence traits.

How are bases organized to code for proteins?

Bases are grouped in sets of 3 called triplets, where each triplet contains a different amino acid to build protein chains.

What is the difference between continuous and discontinuous variation?

Continuous variation is a trait that can be numerically measured from one extreme to the other (e.g., Height), whereas discontinuous variation cannot be measured and is grouped into categories (e.g., Eye Colour).

How do asexual and sexual reproduction differ in terms of parents required and offspring variation?

Asexual reproduction requires one parent and produces offspring with no variation, while sexual reproduction requires two parents (male and female) and produces genetically unique offspring.

What is the process of DNA replication?

An enzyme splits the DNA by breaking hydrogen bonds, new nucleotides bond with the split pairs, an enzyme bonds the nucleotides, and two exact double-helix copies of DNA are produced.

Why is DNA replication considered semi-conservative?

Because one strand of each new DNA molecule is old (original) while the other strand is new.

What is mitosis, and what type of cells does it produce?

Mitosis is the simple duplication of body/somatic cells for growth and development, forming 2 identical diploid ($2n$) daughter cells with 46 chromosomes.

What is meiosis, and what type of cells does it produce?

Meiosis is cell division where a diploid cell duplicates once and splits twice to produce 4 genetically unique haploid ($n$) cells (sperm or egg).

What are Independent Assortment and Crossing Over in meiosis?

Independent Assortment is the random alignment of maternal and paternal homologous chromosomes,

while Crossing Over is the swapping of DNA between homologous chromosomes for allele variations.

What are Haploids and Diploids

Haploids = A single set of chromosomes, represented as “n'“

Diploids = Cells with 2 sets of chromosomes, “2n”

What are mutagens, and what examples are provided in the notes?

Mutagens cause mutations; examples include chemicals (cigarette fumes), ultraviolet light (overexposure to sun), and radiation (from x-rays or radioactive materials).

How do somatic cell mutations differ from gametic cell mutations regarding inheritance?

Somatic cell mutations are not passed on to offspring and die with the individual, whereas gametic cell mutations can be inherited by offspring if the affected gametes are fertilized.

What are the three types of mutations described in the notes?

Silent (no physical effect), Harmful (negatively affects the individual, e.g., cancer), and Beneficial (aids survival, e.g., resistance against Malaria).

What is the difference between a genotype and a phenotype?

Genotype is the specific pair of alleles present in an individual's genetic makeup, while phenotype is the physical showing of a characteristic.

What is the difference between heterozygous and homozygous genotypes?

Heterozygous means having 2 different alleles in a genotype (e.g., Bb), while homozygous means having 2 of the same alleles (e.g., Homozygous Dominant BB, Homozygous Recessive bb).

Putting it ALL Together: Process from Organism to Genetic Variation

Chromosomes = Made of DNA, large double helix (twisted ladder) molecule that determines phenotype.

Bases: A - T & C - G; Base order is equal to genetic information.

Gene = Base sequence coding for a trait (For Example, Eye color).

Alleles = Different gene versions (Brown/Blue eyes) from different DNA base sequences; two per trait (one parent each, chromosomes come in pairs).

Genotype = Allele combination which determines Phenotype (Physical Expression).

Dominant (For Example, B) always expressed over Recessive (For Example, b).

Punnett Squares

A way to determine the possible allele combinations/genotypes of 2 individuals offsprings and thus the possible phenotypes

Pure Bred

Individuals with 2 of the same alleles. They are either homozygous recessive or homozygous dominant.

Test Crosses

You can forcibly breed A with B if A is a pure-bred animal. Say A is homozygous dominant, the offsprings with B should not have recessive traits as it will be impossible. If A is homozygous recessive, then we can determine what B is based off the offspring phenotype and how it correlates with the known Genotype.