BIO 1300 Exam #2 Review

Passive Transport

type of transport that doesn’t require energy to transport substances

Simple Diffusion

type of passive transport where the substance passes directly through the phospholipid bilayer

What type of diffusion is osmosis?

simple diffusion

Facilitated Diffusion

type of passive transport where the substance needs the help channel proteins or carrier proteins to pass through the phospholipid bilayer

Active Transport

type of transport that requires ATP (energy) to cross the phospholipid bilayer

What direction do substances using passive transport go from?

high to low; with their gradient

What direction do substances using active transport go from?

low to high; against their gradient

Na+ / K+ Pump

pumps 3 Na+ out and 2 K+ in

The sodium-potassium pump is a separation of what?

ions and charge

Is outside of the cell in a Na-K pump positive or negative?

positive

Is inside of the cell in a Na-K pump positive or negative?

negative

Membrane Potential

Electrical charge difference across a membrane; measured in millivolts (mV)

What is the measure (mV) of a resting cell?

-70 to -90 mV

Where is the energy coming from when a substance doing active transport is using potential energy?

from a concentration gradient

Cotransport

Transport of 2 or more solutes at same time

What two things does cotransport couple?

a substance going down/with its gradient with a substance going against its gradient

Symporter

cotransporter protein that pumps solutes in the same direction

Antiporter

cotransporter protein that pumps solutes in different direction directions

Secondary Active Transport

energy stored from a solute going down/with gradient is used to transport a solute going against its gradient

Vesicles

bubbles inside the cell made of phospholipids that are used to transport stuff around/across the cell

Microtubules

“Train tracks” for intracellular vesicle transport

Exocytosis

release of large molecules or proteins outside the cell; secretion

Endocytosis

brings large molecules & particles into cell

Types of endocytosis

Pinocytosis, Receptor-Mediated Endocytosis, and Phagocytosis

Pinocytosis

“Cell drinking”; Contents of vesicle are random

Receptor-mediated endocytosis

Receptors on cell surface “grab” target molecules; Receptors collected in a vesicle

How is receptor-mediated endocytosis different than pinocytosis?

receptor-mediated endocytosis collects specific molecules in higher concentration

pinocytosis collects random molecules in lower concentration

Phagocytosis

“Cell eating”; Pseudopodia (false feet) extend around food creating a food vacuole

RNA

single stranded, but can wrap around itself to pair; Base pairing; G – C; A – U

DNA

two strands that match up (Complementary to each other); Double helix; Base pairing; A – T; G – C (hydrogen bonds); Order of bases; = info

The order of bases in DNA determines what?

the information that it contains

What end is the phosphate end and what end is the OH end?

5’ end and 3’ end

DNA is synthesized in what direction?

5’ to 3’

New nucleotides are added to what end?

3’ end

Antiparallel

strands run in opposite directions

Chromatin

packed into a chromosome during cell division; Chromosome =; 1 DNA molecule; + proteins

Chromatin fibers

DNA and proteins

Chromosome

1 DNA molecule and proteins

Centromere

narrow part of chromosome, Near middle; where duplicate chromosomes are connected; (right before cell division)

Human Chromosomes

46 per cell; 2 sets of 23

Number of autosomes in a cell

44

Number of sex chromosomes in a cell

2

XX

female

XY

male

Genome

All the genetic information in a cell or an organism

Genomics

study of the genome

Ribosomes

site of protein synthesis, made of proteins and RNA

Where can ribosomes be found?

• free floating

• bound to Rough ER

• bound to Nuclear envelope

Order of making a polypeptide chain

DNA>mRNA>polypeptide

Gene

• Unit of heredity

• Segment of DNA

  • Genetic information

  • Codes for an RNA product

• Recipe for polypeptide

One gene equals how many polypeptides

1 kind of polypetide

Gene Expression

Turning the information in DNA into a working protein

RNA intermediate

coded for by gene that carries information (mRNA) to make a polypeptide

Transcription

Synthesis of RNA from information in DNA; DNA strand = template for RNA

RNA Processing

Pre-mRNA converted to final, functional form; 5’ cap added to 5’ end (Modified guanine nucleotide), poly-A tail added (50-250 adenine nucleotides)

What’s the Nuclear Pore For?

to allow mRNA to move out of the nucleus

Codon

sequences of 3 letters that codes for an amino acid, redundant (different letters can code for the same AA), not ambiguous (one codon only codes for one AA)

Start codon

AUG, Met (Methionine)

Stop codons

tell ribosomes to stop translation

• UGA, UAG, UAA

Genetic Code

Is universal; Same from species to species

Exons

segments that code for AA

Introns

intervening sequences in mRNA that do not code for the final polypeptide

mRNA Splicing

Introns cut out; Exons connected together

Alternative Splicing

Sometimes not all exons are used; Cell can put exons together in different ways

What are the “players” of translation?

mRNA, Ribosomes, tRNAs, and Amino acids

tRNA

Transfers AAs to ribosome (Transfer RNA)

Anticodon

3 letter sequence that matches/binds with a codon

Translation

mRNA to polypeptide, AAs covalently linked to appropriate tRNA, tRNA match with mRNA codons at the ribosome, Add AA to growing chain Ribosome moves along mRNA, codon by codon

When are the large subunit and small subunit of ribosomes together

when bound to mRNA

What are the three binding sites for tRNA

A site, P site, and E site

A site

Entry point for tRNAs bringing next AA

P site

site of growing polypeptide

E site

exit cite

3 stages of Translation

Initiation, Elongation, Termination

Initiation

Ribosomes and 1st tRNA binds to mRNA at the start codon (AUG)

Elongation

tRNA enters A site and binds to codon; Growing chain transferred to A site where a new peptide bond formed; Ribosome shifts to next codon (tRNAs shift position, “Old” tRNA leaves)

Termination

Release factor (Protein that binds to stop codons)

Different Types of Gene Expression

housekeeping genes, inducible genes, tissue-specific genes

Housekeeping Genes

Always expressed in Constant levels, carry out basic metabolic functions, structure

Examples of housekeeping genes

Cytoskeleton proteins (Actin and Tubulin)

Inducible genes

As needed, can be turned on and off, expression levels can be varied

Example of an Inducible gene

• iNOS (Inducible nitric oxide synthase)

  • During inflammation

• Prolactin

  • mammary gland cells

Tissue-specific Expression

• Liver-specific genes: only turned on in liver (But all genes present)

• Hemoglobin: Only RBC

• Pepsin: Only chief cells in stomach

Gene Regulation

Turning Genes On and Off

Prolactin Effect

1. Prolactin binds to receptor

2. Signal is carried by signaling cascade

3. Regulatory protein enters nucleus

4. Transcription

5. Translation

6. Processing/Sorting and Packaging

7. Exocytosis into mammary gland duct

DNA Replication

DNA copying, Cells divide: Growth, Replacement, Healing

• Must duplicate DNA before division

  • 1 set of DNA → 2 DNA copies → 2 daughter cells with 1 copy each

Daughter cells; Double helix “unzips”; Each separate; strand acts as; a template for; a new strand; Nucleotides added 1 by 1; Base-pairing with template; DNA polymerase; DNA Polymerase; Old Strand; New Strand; Incoming Nucleotides; Begins at origin of replication; Multiple origins per chromosome in humans; Replication; bubble forms; as DNA unzips; Spread out; until merge

Steps of DNA Replication

1. Double helix “unzips”

2. Each separate strand acts as a template for a new strand

3. Nucleotides added 1 by 1

   • Base-pairing with template

   • DNA polymerase

   • Begins at origin of replication

     • Multiple origins per chromosome in humans

     • Replication bubble forms as DNA unzips

     • Spread out until merge

Cell cycle

Sequence of events; From formation of a cell to its own division; Varying lengths; Some cells

Interphase

Most of cell cycle; Metabolism and; growth; 3 sub-phases; G1 phase; Normal cell functions; S phase; DNA synthesis; G2 phase; Prep to divide; M; phase; Cell; Division; G1; S; G2

Mitotic (M) Phase

Mitosis = division of the nucleus; Equal distribution of chromosomes; Cytokinesis =; Division of the; cytoplasm; Result =; 2 identical cells; w̅ same #; of chromosomes; Interphase; M; phase; Mitosis; G1; S; G2; Cytokinesis

G0 Phase

Exit cell cycle at G1; Some cells can re-enter; Normal cell; functions; No division; Ex) Neurons

G0 phase

Like a railroad spur; Main Line; Spur

The Phases of Mitosis

4 phases; Prophase; Metaphase; Anaphase; Telophase

Prophase

Chromatin; condenses into; chromosomes; Mitotic spindle; forms; Nuclear envelope; disintegrates; attaches to

Mitotic Spindle

Made of microtubules; and centrosomes; Guides and separates; chromosomes; Xs = Chromosomes; Centrosome

Metaphase

Chromosomes line up on a plane; In center of cell

Anaphase

Duplicate chromosomes; pulled apart; By mitotic spindle; Towards opposite sides

Telophase

Opposite of prophase; Chromosomes uncoil; Nuclear envelope forms; Mitotic spindle disappears

Cytokinesis in human cells

Usually starts with; anaphase / telophase; Cleavage furrow forms; Contractile ring; pinches cell in 2; Proteins

Cell Cycle Regulation

and; Cancer