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105 Cards in this Set
- Front
- Back
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Peroxisome |
Organelles that contain enzymes to break down hydrogen peroxide |
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Lysosome |
Organelles containing digestive enzymes that break down unwanted materials |
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Magnification |
Ratio of an objects image to its actual size |
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Resolution |
The ability to discriminate between two points close together |
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Cell fractionisation |
Separation of cellular organelles by homogenization and centrifugation |
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In vitro |
In glass |
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Identify this molecule |
Cholesterol |
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The Eddin experiment demonstrated... |
Membrane proteins diffuse freely within the membrane |
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Supporting evidence for the endosymbiotic theory... |
Mitochondria replicate like bacterial cells, have their own DNA which is circular, and their own ribosomes |
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Isomers |
Molecules with the same molecular formula but different structures |
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List the four important functional groups |
Hydroxyl, carbonyl, carboxyl, amino |
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The major form of glucose in plants... |
Starch |
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The form glucose takes in animals... |
Glycogen |
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Why are triacylglycerols a major energy source for many organisms? |
Most reduced form of carbon in nature and they pack efficiently |
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The start codon |
AUG (Methionine) |
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The stop codons |
UAA, UAG, UGA |
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What kind of reaction is this? |
Dehydration reaction |
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Which cells does insulin bind to? |
Muscle, fat, neuronal |
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What happens when insulin binds to the alpha subunit? |
Conformational change of the beta subunit, triggering autophosphorylation of tyrosine inside the cell |
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Protein kinase |
Enzyme that transfers phosphate groups from ATP into serine, threonine, and tyrosine |
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Metabolism |
Chemical reactions catalyzed by enzymes which constitute the biological functioning of an organism |
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Catabolism |
Degradative pathway that breaks down complex molecules, releasing energy |
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Anabolism |
Biosynthetic pathway that builds complex molecules, requiring energy |
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Activation energy |
Initial energy needed to start a chemical reaction |
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How do enzymes catalyze reactions? |
By lowering the activation energy barrier |
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🔺G < 0 |
Favourable |
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What is this process? |
Substrate-level phosphorylation |
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Why are leaves green? |
Pigment molecules in chloroplasts absorb blue and red light but reflect green light |
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Inputs of light reactions |
Light, water, NADP+, ADP |
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Inputs of dark reactions |
ATP, NADPH, CO2 |
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Define gene |
Distinct nucleotide sequence forming part of the chromosome |
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What does DNA consist of? |
A polymer made of a nucleotide base, a deoxyribose sugar, and a monophosphate |
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How do the components of DNA attach? |
The hydroxyl group of the nitrogenous base attaches to the 3' carbon atom of the sugar and the monophosphate attaches to the 5' carbon atom |
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What are Chargaff's rules? |
A) the base sequence of DNA varies between species B) the amount of A&T bases are equal to each other and the amount of G&C bases are equal to each other |
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What is the exception to Chargaff's rules? |
Single stranded DNA |
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What are the differences between DNA and RNA? |
RNA can be double or single stranded RNA has ribose sugar instead of deoxyribose RNA has uracil instead of thymine |
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Together what are DNA and RNA called? |
Nucleic acids |
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What does a chromosome consist of? |
A single molecule of double stranded DNA wrapped around histones |
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When in the cell cycle is DNA replicated? |
In the S phase before division |
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What does semi-conservative replication mean? |
Each new double stranded DNA has one old strand that was used as a template to build the new one |
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What does DNA polymerase III do during DNA replication? |
Attaches the phosphate group of each new nucleotide to the 3' hydroxyl group of the previous nucleotide |
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Where does DNA replication start? |
At the origin of replication, a region with a high proportion of A/T base pairs |
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Where are new nucleotides added to the growing strands? |
Replication forks |
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What does helicase do during DNA replication? |
Untwist the double helix at the replication fork |
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What does topoisomerase do during DNA replication? |
Prevents overwinding by stabilising untwisted strands ahead of the replication fork |
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What does RNA primase do during DNA replication |
Synthesizes small strands of RNA that is complementary to the template DNA |
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Which direction does a new strand get synthesized in? |
5' to 3' |
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What is a leading strand? |
A strand being continuously synthesized toward the replication fork |
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What is a lagging strand? |
A strand being discontinously synthesized in small segments away from the replication fork |
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What are the small segments of a lagging strand called? |
Okazaki fragments |
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What does DNA polymerase I do during DNA replication? |
Removes RNA primers from newly synthesized strands |
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What does DNA ligase do during DNA replication? |
Joins together neighbouring fragments of DNA |
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Draw a diagram of a replication fork including fork movement, leading and lagging strands, and okazaki fragments |
Should look like this |
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What does nuclease do in event of a mismatch or mutation? |
Performs nucleotide excision repair by cutting out and replacing sections of DNA |
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Why do mismatches and mutations occur? |
Many environmental factors affect how well DNA polymerase functions and they increase the error rate |
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What are telomeres and why do they exist? |
Long sequences of non-coding DNA at the ends of chromosomes that exist because DNA polymerase can't complete 5' ends of replicated strands |
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What is telomerase and which cells produce it? |
An enzyme that catalyses the lengthening of telomeres that is produced by germ cells |
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What does PCR stand for and what is it used for? |
Polymerase chain reaction, a method used to replicate large amounts of DNA |
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What are the two stages of gene expression? |
Transcription and translation |
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Describe the process that turns genes into proteins |
DNA is transcribed into mRNA which is translated into proteins |
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What is triplet code? |
3-nucleotide long sequences that code for a specific amino acid |
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When is RNA polymerase used? |
During transcription to form a complementary strand of RNA |
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How is RNA synthesis different from DNA replication? |
Each RNA transcript is short (equivelant of one gene in eukaryotes) Uracil instead of thymine RNA has a short lifespan Only a small percent of DNA is transcribed at a time but this can happen many times depending on how much of the protein is needed |
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What signals the start point of transcription? |
Promoter region at the 3' end of the template |
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What are transcription factors? |
Proteins that mediate the binding of DNA polymerase to the promoter |
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What is the transcription initiation complex? |
The combination of RNA polymerase, transcription factors and the promoter |
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What is the point where transcription stops? |
Terminator sequence |
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What is significant about the nucleotide sequences in promoter and terminator regions? |
They have high proportions of A/T base pairs which have easily broken 2 hydrogen bonds |
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Why does RNA synthesis have a high error rate and why is it not a significant problem? |
Errors aren't repaired. Isn't a problem because RNA is synthesized in huge amounts and doesn't last long |
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Why can't eukaryotic mRNA be translated immediately like prokaryotic mRNA? |
Eukaryotes make pre-mRNA which contain noncoding regions called introns that must first be removed |
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What is differential splicing? |
When pre-mRNA is spliced to keep introns or remove exons to produce different amino acids |
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What are two structural RNA molecules and why are they called that? |
Ribosomal RNA and transfer RNA. They have no genes that code for protein synthesis |
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Why is one-gene-one-protein not accurate? |
Some proteins are made of many polypeptides |
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Draw the process of transcription including template strand, mRNA strand, promoter and terminator, RNA polymerase, direction of protein synthesis, and 3' 5' ends |
Should look like this |
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What is the start codon? |
AUG |
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What are the stop codons? |
UAG, UGA, UAA |
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Describe three different types of mutations |
Nonsense: premature stop codon Silent: wrong code but correct AA Insertion: base is added into the sequence causing a frame shift |
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What is an operon? |
A suite of related genes |
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Which glucose polymers are used for storage and structure in plants? |
Starch is storage Cellulose is structural |
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A phospholipid consists of... |
A glycerol and phosphate backbone and a fatty acid tail |
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Why is saturated fat solid at room temperature? |
It doesn't have a double carbon bond |
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What are the major components of biological membranes? |
Phospholipds Cholesterols Carbohydrates Proteins |
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Which three metabolic processes are involved in cellular respiration and where do they occur? |
Glycolysis: in the cytoplasm CTA cycle: in the matrix of the mitochondria ETC: the inner membrane of the mitochondria |
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What are the major inputs and outputs of light reaction? |
Inputs: water, light, ADP, NADP Outputs: oxygen, ATP, NADPH |
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What are the major components of the ETC? |
4 protein complexes and mobile electron carriers |
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How do monomers join to form a polymer? |
Dehydration: the removal of water to make a single molecule |
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When do mutations occur? |
During DNA replication, repair and recombination |
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What are mutagens and give some examples |
Agents that increase mutation e.g. UV light, x-rays, chemicals in tobacco smoke |
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What is a chemical change in a single base pair? |
Point mutations |
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How is an amino acid added to a growing polypeptide chain? |
Hydrogen bonding between mRNA codon and tRNA anticodon |
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Why is the genetic code called degenerate? |
Because 64 codons code for 20 amino acids so not all mutations cause a change in phenotype |
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What's the difference between a silent and a neutral mutation? |
Silent mutations cause the same amino acid to be produced, neutral mutations cause a chemically similar amino acid to be produced |
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How do silent and neutral mutations slow down the rate of translation? |
If rare codons are specified then tRNAs with rare anticodons are required |
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What can a nucleotide pair substitution result in? |
Missense, nonsense, silent |
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What is an example of a pair substitution causing disease? |
Negatively charged Glu being replaced with nonpolar Val which reduces the solubility of hemoglobin and causes clumping resulting in sickle cell anemia |
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Why are insertions and deletions more likely to cause harmful effects than substations? |
They cause frameshifts that alter the entire sequence from that point |
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What are the 7 changes to genotype that cause evolution? |
1. Single nucleotide changes 2. Rearrangements (insertion, deletion, recombination) 3. Acquisition of new DNA through horizontal gene transfer or hybridization 4. Independent assortment during meiosis 5. Recombination 6. Changes in chromosome number and ploidy 7. Changes in allele frequency |
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What is it called when an organism has an extra set of chromosomes? |
Polyploidy |
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What are transposons? |
Major cause of mutations, they are transposable elements that can copy themselves into novel positions in a genome |
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Why are eukaryotic genes off until needed? |
For cell differentiation |
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Define totipotent |
Potential to differentiate into all cell types e.g. zygote |
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Define pluripotent |
Capacity to differentiate into multiple cell types e.g. stem cell |
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What is a Barr body? |
Inactivated X chromosome |
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What is gene dosage compensation? |
Heterochomatinasation of the extra X chromosome to prevent double the protein as males |
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What is acyl-tRNA transferase and what does it do? |
Enzyme that attaches the appropriate amino acid into it's tRNA |
