A & P Exam 2: Cell Biology/Skin

What are some ways that biologists can look at and study cells?

microscopy

What are some cellular components that all cells have?

plasma membrane, nucleus, cytoplasm

What is cytosol?

water-based, gel-like fluid inside a cell that surrounds the internal structures and organelles; also called intracellular fluid

What are some common components of cytosol?

water, dissolved biomacromolecules like lipids, carbs, proteins, ions like sodium and potassium, and small molecules like glucose and amino acids

What is an organelle?

little organ; complex organized structures within cells that have unique shapes and functions

What are the membrane-bound organelles?

endoplasmic reticulum golgi apparatus lysosomes peroxisomes mitochondria

What are the non-membrane-bound organelles?

ribosomes centrosomes proteasome cytoskeleton

What are some general function of cells?

maintain integrity and shape of cell, dispose of waste, obtain nutrients and form chemical structures

Are the shapes of different cells in our body all the same?

no, the shapes vary and are tied to the specific function the cell performs

What advantage might there be to have cells of different shapes?

the unique shapes of the cells allow them to better execute their functions

The cell membrane may be described as the “fluid mosaic model”-what does this name tell you about the structure of a cell membrane?

it’s a diverse and flexible mixture of molecules

Explain why cell membranes can be called phospholipid bilayers?

the membranes contain two layers of phospholipids with hydrophilic heads and hydrophobic tails

Primary function of proteins

transport, enzyme activity, forming channels, acting as receptors, cell-cell regognition

Location of proteins

embedded within the bilayer(integral) or attached to to the plasma membrane and anchored to exposed parts of the integral protein(peripheral)

Primary functions of cholesterol

strengthens plasma membrane and stabilizes it a temperature extremes; stability and fluidity

Location of cholesterol

scattered within the inner hydrophobic(tail) regions of the phospholipid bilayer

Primary functions of carbohydrates

cell recognition, communication, immune responses

Location of carbohydrates

extracellular surface of cell membrane, attached to either glycoproteins or glycolipids

tight junctions, in terms of structure and primary functions.

seals neighboring cells together and prevents substances from passing between them; composed of plasma membrane proteins that form strands/rows and are positioned like spot welds at apical surface around circumference of adjacent cells

desmosomes, in terms of structure and primary functions.

strongly anchors cells together and provides mechanical strength/structural integrity; composed of several proteins that bind neighboring cells, contains protein plaques

gap junctions, in terms of structure and primary functions.

allows small molecules and ions to pass directly between neighboring cells for communication; composed of six integral plasma proteins(coonnexons) that forms a small fluid-filled tunnel that extends across a small gap

What is Brownian motion? How does it lead to diffusion?

random movement of particles caused by collisions with surrounding molecules

Does diffusion occur if there is no concentration gradient? Why not?

no because diffusion requires a difference in concentration between two ares for there to be a net movement of particles

What is a concentration gradient?

the difference in the concentration of a substance between two regions

Does simple diffusion require energy?

no, it is a movement from high to low concentration, with no need for ATP

What characteristics of molecules allow simple diffusion to occur across a cell membrane?

must be small and nonpolar

Is simple diffusion movement with or against the concentration gradient?

simple diffusion is movement with the concentration gradient

Does facilitated diffusion require energy?

no facilitated diffusion does not require energy(ATP)

How does simple diffusion differ from facilitated diffusion?

facilitated diffusion uses transport proteins to assist substances across the plasma membrane(like ions or polar molecules)

Is facilitated diffusion movement with or against the concentration gradient?

facilitated diffusion moves with the concentration gradient; no energy needed

Does osmosis require energy?

no its a passive process

How does osmosis differ from simple diffusion?

osmosis is specifically the movement of water instead of solutes across a semipermeable membrane

Is osmosis movement with or against the concentration gradient?

with

What is osmotic pressure, and what effect does it have on osmosis?

pressure that is applied to prevent water from moving by osmosis; greater solute concentration=greater water pull in=greater osmotic pressure

If one solution is hypotonic to another, what does it mean?

this means that the solute concentration outside of the cell is lower than that inside the cell; could lead to hemolysis; water enters the cell

If one solution is hypertonic to another, what does it mean?

this means that the solute concentration is higher outside the cell than that inside the cell; could lead to crenation; water leaves the cell

If one solution is isotonic to another, what does it mean?

this means that the solute concentration outside the cell is equal the concentration inside the cell; no net movement

Red blood cells would experience hemolysis under what condition?

hypotonic solution because water enters the cells

Red blood cells would experience crenation under what condition?

hypertonic solution because water leaves the cells

Does active transport require energy?

yes it requires ATP because it moves against the concentration gradient

How does active transport differ from simple diffusion?

active transport requires energy while simple diffusion does not

Is active transport movement with or against the concentration gradient?

active transport moves against the concentration gradient, from low to high concentration, which is why it requires energy

Describe the actions of the Na+- K+ Pump, as an example of active transport.

1 ATP is used to pump 3 NA+ out of cell and 2K+ into cell against the concentration gradient

What is secondary active transport?

the movement of one type of substance DOWN its concentration gradient in order to move a different substance UP its concentration gradient

What occurs in symport(cotransport) systems?

two substances move through the same transporter in the same direction

What occurs in anti port(counter-transport) systems?

two substances move through the same transporter in opposite directions

When would endocytosis occur?

when large substances/amounts of substances need to move into the cell; nutrient uptake,

When would phagocytosis occur?

when a cell engulfs a large particle external to the cell

When would pinocytosis occur?

whenever the cell needs to absorb surrounding extracellular fluid, water, and dissolved nutrients

When would receptor mediated endocytosis occur?

when specific molecules called ligands attach to distinct cell surface receptors; uses receptors to bind specific molecules within interstitial fluid and bring molecules into cell

When would exocytosis occur?

when large substances or large amounts of substances need to be secreted from the cell

How are materials created inside a cell brought to the membrane to allow for exocytosis?

Ribosome → rough ER → transport vesicle → Golgi apparatus → secretory vesicle → plasma membrane → exocytosis DOUBLE CHECK PLS

How would increased temperature influence rate of transport across a membrane?

increases diffusion/transport because molecules move faster

How would increased concentration gradient of solute(like lots more solute outside of the cell) influence the rate of transport across a membrane?

steeper gradient increases diffusion

How would larger vs. smaller molecule size influence the rate of transport across a membrane?

smaller molecules will move easier and faster than large molecules

What is cytoplasm?

all cellular contents between plasma membrane and nucleus

Difference between cytoplasm and cytosol?

cytosol is fluid within the cytoplasm, which one is the entire content that fills the cell between membrane and nucleus

What are “inclusions”?

temporary store of molecules like pigments, or droplets of fat and glycogen in the cytosol

What is the benefit of having fairly complex cell organelles?

better efficiency, ability to perform many functions simultaneously, better control of cellular processes, separation of incompatible reactions

Location and Function of mitochondria

synthesizes ATP, located through cytoplasm

Location and Function of ribosomes

protein synthesis, located in cytosol or attached to rough ER

Location and Function of endoplasmic reticulum(smooth and rough)

synthesizes proteins, produces transport vesicles, in cytoplasm

Location and Function of golgi apparatus

packaging proteins, located in cytoplasm

Location and Function of vesicles(including specialized lysosomes, peroxisomes)

store, transport, process materials; located in cytoplasm

Location and Function of cytoskeleton(includes microfilaments and microtubules)

interconnected network of protein fibers, maintains cell shape, provides mechanical stability, organizes organelles, and enables intracellular transport and cellular movement; in cytoplasm

Location and Function of centrioles and centrosomes

typically close to nucleus; organize microtubules within cytoskeleton; helps with cellular division hairlike projections,

Location and Function of cilia and flagella

hairlike projections, cilia is shorter and smaller, flagella is longer and wider; help move substances along

Location and Function of microvilli

plasma membrane; provide more surface area of plasma membrane for more efficient membrane transport

Nuclear envelope(membrane) and pores

double membrane surrounding the nucleus; openings that regulate movement of substances between nucleus and cytoplasm

Nucleolus

spherical dark body within nucleus where subunits of ribosomes are made

Nucleoplasm

fluid inside nucleus

Chromatin

loosely collide genetic material of the nucleus in a non dividing cell

Chromosomes

tightly coiled mass of DNA

How many chromosomes are found in a human cell?

46 chromosomes, 23 pairs

Histones

proteins around which DNA wraps

What type of organic molecule is DNA?

nucleic acid

What are the building blocks/monomers of DNA?

nucleotides

What happens during Transcription of DNA→RNA

1. section of DNA opened

2. RNA polymerase reads 1 DNA strand

3. complimentary RNA strand produced

4. resulting RNA is pre-mRNA

Why is Transcription of DNA→RNA important?

carries genetic instructions from DNA to ribosome

What happens during RNA processing(in nucleus)?

converted to mature RNA before leaving to cytoplasm from translation; 5’ capping, 3’ tailing, RNA splicing

Why is RNA processing(in nucleus) important?

it prepares pre-mRNA to be made into mature mRNA so that it can be translated into a protein and make it stable to withstand the journey to cytoplasm

What happens during Translation of mRNA at ribosome?

1. Ribosome binds mRNA

2. Ribosome reads mRNA codons

3. tRNAs bring appropriate amino acids

4. tRNA anticodons pair with mRNA codons

5. Amino acids are joined by peptide bonds

6. A polypeptide is produced

Why is Translation of mRNA at ribosome important?

converts the genetic information in mRNA into proteins that the cell needs to function, grow, and repair itself

What is the role of the ER during final processing and shipping of the protein?

folding and processing

What is the role of the transport vesicles during final processing and shipping of the protein?

carries protein from ER to golgi

What is the role of the golgi complex during final processing and shipping of the protein?

modifies, sorties, and packages protein

What is the role of the secretory vesicle during final processing and shipping of the protein?

carries finished protein to plasma membrane

What is the role of the lysosome during final processing and shipping of the protein?

contains enzymes that break down proteins and other materials that need to be destroyed or recycled

What is the role of exocytosis during final processing and shipping of the protein?

secretory vesicle fuses with the cell membrane, releasing the protein outside the cell

Role of messenger RNA(mRNA)

carries genetic instructions from DNA to ribosome

Role of transfer RNA(tRNA)

brings the correct amino acid to the ribosome; its anticodons pairs with the mRNA codon

Role of ribosomal RNA(rRNA)

combines with proteins to form ribosomes

How is the info in DNA used to place the proper amino acids in the proper sequence when building a protein’s primary structure?

DNA base triplet..mRNA codon..tRNA anticodon..amino acid

Interphase

active portion of the cell cycle that includes the G1, S, and G2 phases, where the cell grows, replicates its DNA, and prepares for mitosis

G1

cells grow and produce new organelles and other structures need for DNA replication; replication of centrioles to produce two centriole pairs is also initiated during this phase

S

double strands of DNA are copied in a process called DNA replication, similar process to transcription

G2

centriole replication is completed and enzymes and other structures needed for the mitotic phase of cell division are synthesized

When and why do cells replicate their DNA?

during S phase of interphase, so that each daughter cells has a complete copy of genetic information

DNA replication is semiconservative-what does this mean?

half of the original DNA is conserved in each new daughter DNA molecule: one original.parent strand and one new/daughter strand

What is the purpose of mitosis?

to produce two genetically similar daughter nuclei, each with the same chromosome number as the original nucleus