Ch. 3 - Cell Structure and Genetic Control

These flashcards cover key concepts related to cell structure, genetic control, protein binding, organelle functions, and cellular division, based on lecture notes.

What are ligands in the context of protein binding? Give me an example of a ligands.

Molecules or ions that non-covalently bind to proteins. Example is Hormones. (All hormones are ligands)

What is protein binding?

Ability to bind various molecules and ions to specific sites on the surface of protein molecules

Forms the basis for wide variety of functions performed by proteins

What is a binding site?

Specific region to which a ligand binds

Define specificity in relation to ligand-protein binding.

The degree to which a protein prefers one ligand over others.

What does affinity measure in protein-ligand interactions?

The strength of the binding between a ligand and a protein.

What is percent saturation?

The fraction of binding sites that are occupied at one time.

What occurs during allosteric modulation?

A regulatory molecule binds to an allosteric site, changing the functional site's activity through conformational change (shape change)

How does covalent modulation affect protein function?

By adding a phosphate group to a protein (phosphorylation) that is catalyzed by an enzyme (kinase). Activates/Inhibits activity

What is the difference between agonists and antagonists?

Agonists activate a response while antagonists block effects.

What is the 'fluid mosaic model' in reference to?

The structure of the plasma membrane as a dynamic, constantly changing arrangement.

What is the function of the plasma (cell) membrane?

Structural support, transport (regulates what comes in/out of the cell), and enzymatic control of processes

What are the components of the plasma membrane?

• Phospholipid bilayer → hydrophobic tails attracted to each other with hydrophilic heads

• Cholesterol - allows flexibility in the plasma membrane

• Embedded proteins that have specialized functions and selective transport through protein content

What are 2 modifications to a cell membrane that is vital to their function?

• Cilia and flagella are motorized protein structures that help facilitate movement. Cilia helps to move substances (such as mucus) across the surface of some organs. Flagella help sperm cells propel through its environment.

• Microvilli increase surface areas which help epithelial cells absorb nutrients.

What is the function of lysosomes?

Garbage disposal of the cell! Breaks down and digests proteins and other worn out organelles. Reuses those nucleotides

What is the function of peroxisomes?

Site of oxidation reactions (detoxifies harmful molecules and breaks down hydrogen peroxide)

Define the role of ribosomes in a cell. What are the two types?

Site of polypeptide (protein) synthesis. The two types are free ribosomes and fixed ribosomes on the endoplasmic reticulum

What is the function of rough endoplasmic reticulum?

Assists synthesis of proteins

What is the function of smooth endoplasmic reticulum?

Detoxification, lipid synthesis, and calcium storage in your muscles

What is the function of Golgi complex?

Shipping and receiving area! They receive vesicles that pinch off the rough ER. They can modify proteins by adding a carbohydrate or lipid. Once ready, they ship off to outside of cell.

What is the function of mitochondria? (Also explain a bit about the structure of mitochondria)

Site of aerobic ATP synthesis. There is 2 membranes (external and internal plasma membrane) that help with energy production by creating an electrochemical gradient within the intermembrane space.

What is the function of cytoskeleton?

Cytoskeleton is composed of filaments and proteins that provide structural support of the cell. They determine the shape of the cell.

What is the function of the cell nucleus?

Storage of DNA

What is the function of the nucleolus?

• Site of ribosome subunit synthesis

• Contains DNA that codes for ribosomal RNA (rRNA)

• Produces two ribosomal subunits

• Ribosomes can exit through the pores in the nucleus

What is the difference between genome, genes, chromatin, DNA, and chromosomes?

• DNA is a polymer with 4 different bases

• Genome is the collection of ALL the genes in your DNA

• Genes are a portion of DNA that codes for a protein (like an instruction set for building more proteins)

• Chromatin is the threadlike material (protein wrapped with DNA) that makes up chromosomes

• Chromosomes are highly compacted forms of chromatin (one of 23 strands of DNA)

What is gene expression?

Takes the instructions within a gene and turns it into a protein

What is a codon?

Three letter words (base triplet) in DNA or mRNA that calls out one of the 20 amino acids

What determines the primary structure of a protein?

Sequence of bases (codon) in the mRNA

What is the difference between mitosis and meiosis?

Mitosis is a cell division producing two identical daughter cells; meiosis produces gametes (sex cells) with half the chromosome number → happens in gonads and ovaries