Exam 3 Definitions

Question 1

Lipids, what are they defined by

Answer 1

organic molecules that have limited solubility in water and can be isolated from organisms by extraction with nonpolar organic solvents
- insoluble in water but soluble in organic solvents
- defined by solubility

Question 2

Micelles

Answer 2

spherical structures containing amphipathic molecules arranged with hydrophobic regions in the interior and hydrophilic head groups on the exterior

type of hydrophobic interaption in lipids

Question 3

vesicles

Answer 3

forms spontaneously when a bilayer sheet folds back on itself to form a hollow sphere
- a small fluid-filled bladder, sac, cyst, or vacuole within the body

type of hydrophobic interation in lipids

Question 4

bilayers

Answer 4

a continuous double layer of lipid molecules in which membrane proteins are embedded.

Question 5

integral proteins vs peripheral proteins ( how are they linked)

Answer 5

Integral proteins embed in or pass through the membrane
- peripheral: proteins are bound to the membrane primarily through
noncovalent interactions
-Can be linked covalently through myristic, palmitic, or prenyl groups

Question 6

membrane proteins

Answer 6

proteins being associated or attached to the membrane of a cell or an organelle inside the cell.
- most functions associated with the membrane require membrane proteins

Question 7

Lipid rafts

Answer 7

Specialized microdomains that can be found in the external leaflet of the plasma membrane
- dynamic assemblies of proteins and lipids that float freely within the liquid-disordered bilayer of cellular membranes
- Can be up to 50% of the cell surface

help maintain cellular function

Question 8

Passive Transport

Answer 8

A type of membrane transport that required no energy and moves WITH the concentration gradient ( facilitated and simple diffusion)

Question 9

Simple Transfusion

Answer 9

propulsion of each solute by random molecular motion from an area of high concentration to an area of low concentration
- O2 and CO2
- no protein channel

Question 10

Facilitated Diffusion

Answer 10

uses channel proteins to move large or charged molecules down/ WITH their concentration gradient
- Ex. chemically gated Na+ channel and voltage-gated K+ channel
- no energy

Question 11

Active Transport

Answer 11

uses energy to transport molecules against a concentration gradient

Question 12

Gene

Answer 12

a DNA sequence that contains the base sequence information to code for a gene product, protein, or RNA

Question 13

Genome

Answer 13

The complete DNA base sequence of an organism

Question 14

transcriptome

Answer 14

The total RNA transcripts for an organism ( the full range of messenger RNA, or mRNA)

Question 15

proteome

Answer 15

the entire set of proteins synthesized

Question 16

metabolome

Answer 16

the sum total of low molecular weight metabolites produced by the cell

Question 17

Purine

Answer 17

DNA amine base (adenine, and guanine) double rings

Question 18

pyrimidine

Answer 18

DNA amine base (cytosine and thymine) single rings

Question 19

Point mutation

Answer 19

small single base changes ( mutation)
Subgroups: transition and transversion mutations

Question 20

frameshift mutation

Answer 20

indels( insertion or deletion) that occur within the coding region that are not divisible by three

Question 21

transition vs. transversion point mutation

Answer 21

transition: caused by deamination, leading to purine for purine or pyrimidine for pyrimidine substitutions
Transversion mutations occur when a purine is substituted for a pyrimidine or vice versa

Question 22

Codon

Answer 22

A sequence of three consecutive nucleotides in a DNA or RNA molecule that codes for a specific amino acid

Question 23

anticodon

Answer 23

a sequence of three nucleotides forming a unit of genetic code in a tRNA molecule, corresponding to a complementary codon in messenger RNA.

Question 24

Monocistronic

Answer 24

( mRNA) Eukaryotes, contains only one structural gene, coding for a single polypeptide chain

Question 25

polycistronic

Answer 25

(mRNA) In prokaryotes, two or more separate proteins are encoded on a single molecule of messenger RNA

Question 26

Chromosome

Answer 26

a threadlike structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes. in which the genetic traits encoded in DNA are maintained and transmitted from one generation to the next

Question 27

nucleosome

Answer 27

a section of DNA that is wrapped around a core of proteins (inside the nucleus) -formed by the binding of DNA and histone proteins

Question 28

chromatin

Answer 28

Each eukaryotic chromosome consists of a single, linear DNA molecule complexed with histone proteins to form nucleosomes ( this complex is called chromatin)

Question 29

Semiconservative replication

Answer 29

After the two strands have separated, each serves as a template for synthesis of a complementary strand -DNA replication occurs before cell division and has a similar mechanism in all organisms

Question 30

Replication fork

Answer 30

New nucleotides line up on each strand in a complementary manner, A to T / G to C, and two new strands begin to grow from the ends of the bubble - where DNA replication takes place

Question 31

Leading vs. lagging strand (Okazaki fragments)

Answer 31

(DNA replication) Leading Strand: The complement of the original 3’ to 5’ strand is synthesized continuously in a single piece to give a newly synthesized copy Lagging strand: complement of the original 5’ to 3’ strand is synthesized discontinuously in small pieces called Okazaki fragments that are subsequently linked by DNA ligases to form the lagging strand

Question 32

Template/nontemplate strands

Answer 32

- The template strand (-) of DNA is antiparallel to the new RNA strand - The non-template strand (+) has the same base sequence as the RNA, except the transcript has U for T

Question 33

coding/noncoding strands

Answer 33

The DNA strand that contains the gene is the coding strand/ sense strand The DNA strand that gets transcribed to give RNA is called the noncoding/ antisense strand

Question 34

sense/antisense strands

Answer 34

sense/coding/nontemplate strand antisense strands/noncoding strands/template

Question 35

Constitutive genes

Answer 35

routinely transcribed because they code for gene products required for normal cell function

Question 36

inducible genes

Answer 36

a gene whose expression is either responsive to environmental change or dependent on the position in the cell cycle

Question 37

repressible genes

Answer 37

those in which the presence of a substance (a co-repressor) in the environment turns off the expression of those genes

Question 38

Alternative splicing

Answer 38

a cellular process in which exons from the same gene are joined in different combinations, leading to different, but related, mRNA transcripts - removal of different combinations of introns