biol 1406 exam 2

The 4 components of cell theory

All living organisms are composed of one or more cells, the cell is the basic unit of life, new cells arise from pre-existing cells, and cells carry hereditary information that is passed on during cell division

Cells use molecules to do what 3 main jobs

Chemical, transport, and mechanical work

4 implications of cell theory

Functions of all cells are similar, life is continuous, origin of life was the origin of cells, cells are tiny

WHY is cell size limited by surface area to volume

As a cell volume increases, chemical activity increases, along with the need for resources and waste removal. Surface area becomes limiting. Thus large organisms consist of many small cells

Which increases faster: the diameter of a cell or the volume of a cell

The volume of a cell increases faster than its diameter bc the volume scales with the cube of the diameter, while the diameter is a linear measurement

Do particles move easily over long distances

No, diffusion is extremely slow over long distances

What is resolution

The ability to distinguish two adjacent structures or points as separate from another

What is the resolution for a human eye, typically

200 micrometers (0.2 mm)

How is microscopy essential for pathology

It allows visualization of cells, tissues, and microorganisms to diagnose diseases by identifying cellular abnormalities, and subtle differences in cell structure and color

Bright field microscopy

Light passes directly through these human cells. Unless natural pigments are present, there is little contrast and details are not distinguished

Phase contrast microscopy

Contrast in the image is increased by emphasizing differences in refractive index, thereby enhancing light and dark regions in the cell

Differential interference - contrast microscopy

Uses two beams of polarized light. The combined images look as if the cell is casting a shadow on one side

Stained bright-field microscopy

A stain enhances contrast and reveals details not otherwise visible

Fluorescence microscopy

A natural substance in the cell or fluorescent dye that binds to a specific cell material is stimulated by a beam of light, and the longer-wavelength fluorescent light is observed coming directly from the dye

Every cell has what 2 parts

Plasma membrane and cytoplasm

What is the overlying function of cell membrane

The outer boundary of every cell, selectively permeable barrier, allows cells to maintain a constant internal environment, has proteins for binding and adhering to adjacent cells

4 important roles for cell membrane

Selective permeability, cell signaling and communication, structural support, and creating compartments

3 domains of living things

Bacteria, archaea, eukarya

Is prokarya a domain? What 2 domains are prokaryotic

No, bacteria and archaea

Do prokaryotes have a nucleus

No

Do eukaryotes have a nucleus

Yes

The 4 groups of organisms found in domain Eukarya

Protista, fungi, plantae, and animalia

Organelle definition

a tiny, specialized structure within a cell that performs a specific function

How does division of labor in organelles help eukaryotes be more complex?

By compartmentalizing different tasks, organelles create specialized micro-environments where incompatible chemical reactions can occur simultaneously and more quickly

The size typical prokaryotic cell is

0.1 to 5.0 micrometers

Are prokaryotes single cell or multicellular? Can prokaryotes associate in chains?

Single celled, some can associate in colonies and certain types can even form chains that appear multicellular

prokaryotes have what 4 structures

Plasma membrane, cytoplasm, ribosomes, and dna

What is nuceloid

The region within a prokaryotic cell that contains genetic material (DNA)

How is nucleoid similar to nucleus? How are they different?

They are similar bc they are both regions within a cell that house the genetic material and are involved in regulating cell activity through controlling gene expression and dna replication. They differ in structure, the nucleus is a membrane-bound organelle in eukaryotes, while the nucleoid is a region without a surrounding membrane in prokayotes

Cytoplasm

Jelly like substance inside the cell membrane that surrounds the organelles

Is cytoplasm only in prokaryotes

No, its found in both

Ribosomes

Cellular structures responsible for protein synthesis, or translation. They are made of ribosomal rna and proteins, consisting of a large of a small subunit. They use genetic information from messenger rna to link amino acids together in the correct sequence to create proteins

Does cytoplasm move inside a cell? How does this help the cell function?

Yes, helps transport nutrients, organelles, and other materials to different parts of the cell

Cell wall for a prokaryote

A rigid layer outside the plasma membrane that provides structural support, maintains cell shape, and protects the cell from mechanical stress

what chemicals make up bacterial cell walls

Peptidoglycan

What is the capsule found in some bacteria, what does it do

A sticky, polysaccharide-based outer layer that protects bacteria from host immune cells and environmental stressess

How are membranes a physical barrier to hydrophilic substances, like water?

Bc of the hydrophobic (water fearing) nature of its interior

Explain how membranes are functional barriers that help the cell function

By controlling the passage of substances, maintaining specialized internal environments, and enabling communication with the outside world

What 3 constituents do membranes have, regardless of type of membrane

Lipids, proteins, and carbohydrates

Lipids establish physical integrity: what does this mean?

Refers to how lipids, particularly phospholipids, form the cell membrane, which acts as a protective and flexible boundary for the cell

Define and explain the fluid mosaic model of membrane structure

The plasma membrane as a flexible and dynamic structure composed of mosaic components, including phospholipids, cholesterol, proteins, and carbohydrates. These molecules are constantly moving laterally within the membrane, giving it a fluid like character

What is amphipathic as it relates to phospholipids

The molecule has both a water-attracting (hydrophilic) head and a water-repelling (hydrophobic) tail. This dual nature allows phospholipids to spontaneously form the lipid bilayer of cell membranes

What part of the phospholipid is hydrophilic

The head

Why is the head of phospholipid hydrophilic

It contains a negatively charged phosphate group, which is polar and attracts water molecules through hydrogen bonds

What part of the phospholipid is hydrophobic

The tails

What makes the tails hydrophobic

It consists of nonpolar fatty acid chains that do not mix with water

Functions and interactions of collagen

Provides structural support and tensile strength to connective tissues like skin, bones, tendons, and ligaments. Has active roles by interacting with cell surface receptors, enzymes, and other extracellular matrix components

Functions and interactions of cholesterol

Provides structural integrity to cell membranes, acting as a precursor for steroid hormones. Interacts with lipids and proteins to maintain its functions and transport within the body

Functions and interactions with glycolipid

Function in cell recognition, communication, and stability. They interact with other cells, molecules, pathogens and toxins

Functions and interactions with glycoprotein

Proteins with attached sugar molecules that perform in cell-to-cell recognition, adhesion, and signaling. Interact cell-to-cell, receptor-ligand, immune system, and infections

Functions and interactions with the cytoskeleton

Provide structural support, maintains cell shape, and enables cell movement and internal transport. Interactions between filament types, interaction with the nucleus

Functions and interactions with cytoplasm

Holds and suspends organelles and supports cell shapes. Interacts with the cytoskeleton to provide structure and transport pathways

What is the “bilayer” of phospholipids

The fundamental structure of cell membranes, consisting of two layers of phospholipids with their hydrophilic heads facing outwards and hydrophobic tails facing inward

Why does bilayer form

Bc of the amphipathic nature of the phospholipid molecules and the hydrophobic effect

How does bilayer affect membrane function

By creating a stable but fluid barrier, regulating the passage of molecules, and modulating the function of embedded proteins

While membranes have the same basic plan, what can change between membrane types, or as the membrane shuffles through endomembrane system

Their composition can change depending on their location and function. As it moves through the endomembrane system, it is dynamically modified, resulting in different membranes with distinct characteristics

Which type of fatty acids pack closely together? Why?

Bc they have a straight, linear shape due to having no double bonds between carbon atoms. It allows the fatty acid molecules to stack neatly, increasing the intermolecular forces between them , which makes them solid at room temp

Which type of fatty acids cannot pack closely together? Why?

Unsaturated fatty acids, due to the presence of one or more double bonds in their hydrocarbon chains

Who has cholesterol in membrane: plant or animal

Animal

How does lipid composition affect membrane fluidity

Primarily through fatty acids cannot pack saturation and cholesterol content. Unsaturated fatty acids with their “kinks”, increases fluidity by preventing tight packing. While saturated fatty acids pack tightly, decreasing fluidity

What makes a membrane less fluid (more stable structure)

Higher levels of saturated fatty acids, cholesterol (at warmer temps), and lower temps

What makes a membrane more fluid, easier for things to cross

A membrane becomes more fluid with a higher proportion of unsaturated fatty acids, a higher temperature, and the presence of cholesterol in cold conditions

As temperatures cool, what happens to membrane fluidity? How does the cell compensate

Decreases bc phospholipids pack more closely and their movement is restricted. Increasing the proportion of unsaturated fatty acids in their membranes, which increases fluidity

Are proteins the same on the inside and outside of plasma membrane

No, the proteins are not the same on the inside and outside of the plasma membrane

What parts of proteins allow them to interact with phospholipid bilayer, especially the tails

The hydrophobic parts of proteins, which contain non polar amino acids

Where are hydrophilic regions of proteins in membranes

On the exterior surfaces exposed to the aqueous environments both inside and outside the cell

Define integral proteins

Proteins that are permanently embedded within the cell spanning its entire thickness

Examples of information prokaryotes and eukaryotes get from their environments

Chemical signals, light, temperature, and population density

What determines if a cell responds to a signal

It’s specific collection of receptor proteins and it’s set of intracellular signaling molecules

What is a receptor in terms of cells

A protein on a cell’s surface or inside it that binds to a specific signaling molecule (ligand) and triggers a specific response within a cell