Lecture 2: Chemical Context of Life and Inheritance

Flashcards testing knowledge on biological macromolecules, central dogma, ploidy, inheritance, genetics terminology, and Punnett square crosses from Lecture 2.

What are the four major biological molecules?

Proteins, Carbohydrates, Fats (Lipids), and Nucleic acids.

What are proteins composed of, and how are they synthesized in the cell?

Proteins are chains of amino acids synthesized through gene expression in the sequence $\text{DNA} \rightarrow \text{RNA} \rightarrow \text{Proteins}$.

Which specific protein serves as an example of providing a unique trait in the Antarctic toothfish?

Antifreeze proteins.

What are the specific biological functions of the proteins Actin, Myosin, Keratin, and Casein?

Actin and Myosin function in motion, Keratin provides structural support, and Casein functions in storage.

What is the Central Dogma of biology, and what are its two main stages?

The Central Dogma is the process by which DNA codes for a protein via an mRNA intermediate. Its two stages are Transcription ($\text{DNA} \rightarrow \text{mRNA}$) and Translation ($\text{mRNA} \rightarrow \text{protein}$).

What building blocks make up carbohydrates, and what are their two primary functions?

Carbohydrates are made of chains of glucose molecules. Their primary functions are short-term energy storage and structural support.

How do Cellulose, Starch, Chitin, and Glycogen differ in function and host organism?

Cellulose provides structural support in plants (e.g., leaves of corn); Starch provides energy storage in plants (e.g., kernels of corn); Chitin provides structural support in animals (e.g., crab shells); Glycogen provides energy storage in animals.

What are the primary biological functions of Phospholipids, Triglycerides, and Steroids?

Phospholipids form cell and organelle membranes; Triglycerides store long-term energy; Steroids (such as cholesterol, testosterone, and cortisone) regulate growth, reproduction, and development.

What are the primary functions of nucleic acids, and what monomers make them up?

Nucleic acids are chains of nucleotides ($\text{A}$, $\text{T}$, $\text{C}$, $\text{G}$, and $\text{U}$). They function in genetic information storage (DNA), genetic information carrier (RNA), and protein synthesis (RNA).

What are the four criteria required for evolution by natural selection?

1. Variation of a trait exists. 2. Traits are heritable. 3. More offspring are born than survive and reproduce. 4. Survival and reproduction are non-random (advantageous variation).

What is the ultimate source of genetic variation in a population?

Mutations.

Despite generating necessary genetic variation, what impact do mutations typically have on an organism?

Mutations almost always cause early death or lower the reproductive success of an organism.

What is ploidy, and how does it compare between human body cells and fungi?

Ploidy is the number of sets of chromosomes a cell has. Human body cells are primarily diploid ($2n$), whereas fungi are primarily haploid ($n$).

How do genotype and phenotype differ?

Genotype is the genetic makeup of an individual, whereas phenotype is the physical appearance, which depends on the genotype and its interaction with the environment.

What is the difference between a homozygote and a heterozygote?

A homozygote has two copies of the same allele, while a heterozygote possesses two different alleles.

How are DNA, chromosomes, and genes defined and related?

DNA is the molecule carrying genetic information; a chromosome is a thread-like structure composed of DNA and proteins; a gene is a specific unit of heredity located on DNA that determines organism traits.

In a cross between two heterozygous individuals ($\text{Yy} \times \text{Yy}$), what are the expected phenotypic and genotypic ratios?

The phenotypic ratio is $3:1$ (dominant to recessive), and the genotypic ratio is $1:2:1$ ($\text{YY}:\text{Yy}:\text{yy}$).

In dogs, black fur ($\text{B}$) is dominant over brown fur ($\text{b}$). If a dog named Dany has brown fur, what is her genotype?

$$\text{bb}$$

If Dany (genotype $\text{bb}$) has parents that both have black fur, what must both of her parents' genotypes be?

Both parents must be heterozygous ($\text{Bb}$).

In peas, purple flower allele ($\text{P}$) is dominant over white flower allele ($\text{p}$). A purple-flowered plant is crossed with a white-flowered plant, yielding 2 purple-flowered and 1 white-flowered offspring. What are the genotypes of the parent plants?

$\text{Pp}$ (purple parent) and $\text{pp}$ (white parent).