Biology 3 Lecture Review: Biomolecules, Mutations, Genetics, and Molecular Genetics

Comprehensive practice flashcards for Grade 12 Health Sciences Biology 3, covering biomolecules, gene and chromosome mutations, Mendelian and non-Mendelian genetics, chromosomal aberrations, and molecular genetics.

What is the defining chemical characteristic of organic macromolecules?

They are molecules containing Carbon (C) and Hydrogen (H).

How do dehydration synthesis and hydrolysis differ in biological polymer reactions?

Dehydration synthesis joins molecules together by removing water, whereas hydrolysis breaks molecules apart by adding water.

What are the stoichiometric formula and general formula for carbohydrates?

The stoichiometric formula is $(CH_2O)_n$ and the general formula is $CH_2O$.

What structural feature distinguishes an aldose from a ketose monosaccharide?

An aldose has a carbonyl group ($C=O$) at the end of the carbon chain with a hydrogen atom, whereas a ketose has a carbonyl group ($C=O$) located between two carbon atoms.

What are the common names for the monosaccharides glucose, galactose, and fructose?

Glucose is Blood Sugar, Galactose is Milk Sugar, and Fructose is Fruit Sugar.

Which monosaccharides combine to form sucrose, lactose, and maltose?

Sucrose = Glucose + Fructose; Lactose = Glucose + Galactose; Maltose = Glucose + Glucose.

What are the main plant and animal storage polysaccharides described in the lecture?

Starch is the plant carbohydrate storage (composed of amylose and amylopectin), and glycogen is the animal carbohydrate storage system.

Why is the fake fat Olestra indigestible by human digestive enzymes?

In Olestra, fatty acids are bonded to sucrose instead of glycerol, resulting in large, bulky, highly insoluble molecules that lipase enzymes cannot break down.

Which chemical group or fatty acid is attached to each carbon of the glycerol backbone in a phospholipid?

Carbon 1 holds a saturated fatty acid tail, Carbon 2 holds an unsaturated fatty acid tail, and Carbon 3 holds the phosphate group.

What is the characteristic carbon skeleton structure of steroids?

A 17-carbon skeleton arranged in four fused rings, consisting of three 6-carbon rings and one 5-carbon ring.

What four central components are covalently bonded to the alpha carbon of an amino acid?

An amino group ($-NH_2$), a carboxyl group ($-COOH$), a hydrogen atom ($-H$), and a variable side chain (R-group).

How do essential and non-essential amino acids differ according to dietary needs?

There are 9 essential amino acids that cannot be synthesized by the body and must be obtained from the diet, and 9 non-essential amino acids that can be synthesized by the body.

What amino acid chain length differentiates a peptide from a protein?

Peptides consist of fewer than 50 amino acids, whereas proteins consist of more than 50 amino acids.

What specific point mutation causes Sickle Cell Disease?

A DNA sequence change from CAC to CTC produces mRNA encoding GUG instead of GAG, which specifies valine instead of glutamic acid.

What is the structural difference between a transition point mutation and a transversion point mutation?

A transition occurs when a purine replaces a purine (A to G or G to A) or a pyrimidine replaces a pyrimidine (C to T or T to C); a transversion occurs when a purine replaces a pyrimidine or vice versa.

What defines a nonsense mutation?

A point mutation that changes a codon specifying an amino acid into a stop codon (UAA, UAG, or UGA in mRNA), producing a shortened protein.

Who is known as the Father of Genetics, and when did he start his pea plant experiments?

Gregor Mendel, who started his experiments in 1856 using garden pea plants.

What are the genotypic and phenotypic ratios resulting from a monohybrid cross of two heterozygous parents ($Bb \times Bb$)?

The genotypic ratio is $1\,\text{BB} : 2\,\text{Bb} : 1\,\text{bb}$ and the phenotypic ratio is $3:1$.

What phenotypic ratio results from a dihybrid cross between two double-heterozygous parents ($RrGg \times RrGg$)?

A classic $9:3:3:1$ phenotypic ratio.

What is the criss-cross inheritance pattern?

A mechanism where an X-linked recessive trait skips a generation by passing from an affected father to a carrier daughter, who then passes it to an affected grandson.

What is teratology?

The scientific study of congenital malformations, structural abnormalities, and developmental defects present at birth.

What are the three autosomal trisomies named in the lecture?

Patau Syndrome (Trisomy 13), Edward Syndrome (Trisomy 18), and Down Syndrome (Trisomy 21).

What specific chromosomal translocation product is associated with Chronic Myelogenous Leukemia?

The Philadelphia chromosome.

What key piece of evidence did Rosalind Franklin contribute to the discovery of DNA's structure?

She captured Photo 51 in 1952 using X-ray crystallography, providing pivotal evidence for the double-helix structure of DNA.

What are the exact dimensions of the DNA double helix specified in the Watson-Crick Model (1953)?

DNA is a double helix with a width of $2\,\text{nm}$ and $3.4\,\text{nm}$ per helical turn, containing 10 base pairs per turn.

How many hydrogen bonds connect complementary base pairs in DNA?

Adenine and Thymine ($A=T$) are joined by 2 hydrogen bonds, while Guanine and Cytosine ($G \equiv C$) are joined by 3 hydrogen bonds.

What are the ribosome subunits and the catalytic rRNA component in eukaryotic 80S ribosomes?

Eukaryotic 80S ribosomes are composed of 60S and 40S subunits, and the 28S rRNA component acts as a ribozyme.