BIOL 1P91 Final
What is photosynthesis?
process by which some organisms capture the energy from the sun (solar) and transform it into energy (chemical) that can be used by living things
What is a producer
an organism that makes its own energy-rich food components using the sun's energy. ex.) green plants
What are autotrophs
- organisms that make their own food
Phototroph: use solar energy (photosynthesis) to get energy
Chemotroph: use different chemical processes to get energy
What is a consumer:
- an organism that obtains its energy from consuming other organisms
What are heterotrophs
- organism that must take in food to meet their energy needs
- consume autotrophs, other heterotroph (carnivores), or both (omnivore)
Explain the cause of the dinosaur extinction
- a huge asteroid is thought to have hit Earth near Mexico which sent up so much dust that the sun was blocked for many years
No sun = no food = no dinos
Define the biosphere
- regions on the surface of the Earth and atmosphere where living organisms exist
What are the two stages of photosynthesis? Where do they occur?
1. Light reactions (in thylakoid membranes): light is absorbed by chlorophyll and converted to ATP and NADPH
2. Dark reactions(Calvin cycle) (in stoma): ATP and NADPH used to drive the synthesis of carbohydrates
Where does the majority of photosynthesis occur?
internally in the leaves, in the mesophyll
T/F, shorter wavelengths radiation carries more energy per unit time than longer wave length radiation.
TRUE
Which of the photosystems, PSI or PSII was discovered first and which one is used in the 1st step of photosynthesis?
PSI - discovered first
PSII - in 1st step of photosynthesis
What is the primary goal of PSI?
- to make NADPH
What 3 things are made after the light-dependent reactions?
Oxygen, NADPH, ATP
Why is there said to be a Z-scheme in the process of photosynthesis?
- a zigzag shape of energy curve
- photosynthesis involves increases and decreases in the energy of an electron as it moves from PSII through PSI to NADPH
- involves light exciting electrons
Explain the dark reactions briefly
- creating carbohydrates through the calvin cycle
- CO2 is incorporated
- requires massive input of energy
- product is glyceraldehyde-3-phosphate (G3P) (made into glucose later)
- 3 phases: Carbon fixation, reduction and carbohydrate production, regeneration of RuBP
T/F, RuBisCo can be a carboxylase and an oxygenase
TRUE
What are C4 plants and give an example
- in warm dry climates C4 plants conserve water and prevent photorespiration
- evolved a mechanism to minimize photorespiration
ex.) Bamboo, corn
What are CAM plants?
Crassulacean acid metabolism
- separate processes using time
- open stomata at night
- CO2 enters and is converted to malate
- banks up on CO2 throughout the day to convert it at night
ex.) Cactus
Define inheritance
= the acquisition of traits by their transmission from parent to offspring
- used to have thought to occur through pangenesis (whole body contributes to offspring)
What is the idea of Blending Inheritance and is it false?
that hereditary traits blended together in offspring and continued to be passed down
- not true either!!
Who is Gregor Mendel? What did he study?
- priest
- studied physics and math
- studied pea plants
- "father of modern genetics"
What are three advantages of pea plants?
1. Genetic variation
2. Normally self-fertilizing
3. Ease of making crosses
What is P generation? What is F1 generation? What is F2 generation?
P gen: true-breeding parents
F1 gen: first-generation offspring of a P cross
F2 gen: F1 monohybrids fertilize to produce the F2 generation
Name 3 important ideas from Mendel
1. Traits may exist in two forms, dominant and recessive
2. An individual carries 2 genes for a character/trait, genes have different alleles
3. 2 alleles of a gene separate to give rise to haploid cells and gametes, so each sperm and egg receives only one allele
What is Mendel's Law of Segregation?
2 copies of a gene segregate from each other during gamete formation, so only one allele is given to each gamete
Distinguish between genotype and phenotype
Genotype: genetic composition of individual
Phenotype: characteristics (traits) of an organism that are the result of their genotype ex.) Tall phenotype vs. dwarf phenotype
What were Mendel's two hypotheses for assortment and which one did he actually see?
1. Linked assortment: genes segregate together
2. Independent assortment: genes are independent, so their alleles are randomly distributed into the gametes, ex.) 9:3:3:1
Mendel saw Independent assortment
What is Mendel's Law of Independent Assortment?
the alleles of different genes assort independently of each other during the process that gives rise to gametes
What are autosomes vs. sex chromosomes
Autosomes: pairs of chromosomes found in both sexes
Sex chromosomes: distinctive pair of chromosomes that differs between males and females
How many human chromosomes? How many pairs of autosomes? How many pairs of sex chromosomes?
- 46 chromosomes
- 22 pairs of autosomes
- 1 pair of sex chromosomes
Explain the difference between Wild-type allele and Mutant allele?
Wild-type allele: prevalent allele in a population
Mutant allele: alleles that have been altered by mutation (rare in natural populations)
What is incomplete dominance?
- heterozygote exhibits a phenotype that is distinct and intermediate between the two homozygous phenotypes
- shows different phenotypes at 100%, 50% and 0% protein levels
- red, white, and pink
What is codominance?
- single individual expresses both alleles in a way that leads to BOTH traits in the phenotype
What is polygenic inheritance?
- determined by multiple genes!
- traits that show continuous variation over a range of phenotypes are called quantitative traits
ex.) grain pigmentation in wheat
T/F, calico cats are always female and why?
TRUE
- the gene for coat colour is on the X chromosome
- shows patches where the orange or black allele was inactivated
What is gene linkage? and a linkage group?
gene linkage = when different genes are close together on the same chromosome, they tend to be transmitted as a unit
linkage group = group of genes that usually stays together during meiosis (do NOT follow the law of independent assortment)
Explain noncombinants/parental and recombinants/nonparental types:
Noncombinants: offspring combination of traits has not changed from parental generations (no crossing over between genes)
Recombinants: offspring have a different combination of traits from parental generation (crossing over occurs)
How many cells does the average adult human body contain
10 to 50 trillion cells
What are the two processes of cell reproduction?
1. Mitosis
2. Meiosis
What is cytogenetics
The field of genetics involving microscopic examination of chromosomes
T/F, the biggest chromosomes are the smallest numbers, like chromosome 1 and 2
TRUE
What is a karyotype
- a photographic representation of chromosomes
Diploid vs. Haploid
Diploid: 2 chromosome sets (2N)
Haploid: 1 set of chromosomes (N)
T/F, the Y chromosome is much larger than the X chromosome
FALSE, chromosome X is much bigger than Y
Name the different parts of interphase and then the last part that is not in interphase
Interphase
G1: first gap
S: synthesis of DNA
G2: second gap
M: mitosis & cytokinesis
Differentiate between the terms Mitosis and Cytokinesis
Mitosis = division of one nuclei into two nuclei
Cytokinesis = division of one cell into two
How is cytokinesis different in animal cells compared to plant cells?
Animal cells: cleavage furrow constricts (like a drawstring) to separate cells into two
Plant cells: vesicles from Golgi apparatus form a cell plate, which then forms a cell wall between the 2 daughter cells
T/F, genes are located on the same place on the chromosomes for everybody
TRUE
What is CHIASMA
= the connection between chromosomes that have crossed over (visible during late prophase)
Who proposed the Chromosome Theory of Inheritance?
Boveri & Sutton
What is a locus
physical location of a gene on a chromosome
T/F, diploid multicellular stage = sporophyte and haploid multicellular stage = gametophyte
TRUE
What is genetic material
the "blueprint" for the construction of living organisms
What are the four criteria for genetic material? T.R.I.V
1. Information
2. Replication
3. Transmission
4. Variation
In the 1920s to 1940s, scientists expected _______ to be identified as the genetic material
PROTEIN
Who performed the experiment on Bacterial Transformation?
Griffith
what are the 2 strains of a bacterium (streptococcus pneumoniae)
1. Smooth (S): secretes a capsule, look smooth
= pathogenic: causes disease/infection and kils mice
1. Rough (R): does not secrete a capsule, look rough
= does not cause infection in mice
Which scientists performed a follow-up experiment to Griffith's experiment
Avery, MacLeod, and McCarty
What is transformation:
A process in bacteria where DNA is taken up from the environment and incorporated into the cell
- can be performed naturally and also be induced
What is a genome:
A complete complement of an organism's genetic material
Name the 3 components of nucleotides of DNA
1. Phosphate group
2. Pentose sugar = Deoxyribose
3. Nitrogenous bases
Purines: Adenine, Guanine
Pyrimidines: Cytosine, Thymine
Who proposed the double helix structure of DNA?
James Watson, Francis Crick, Maurice Wilkins
Who performed the experiment on X-ray Diffraction? (taking chemical substances and putting it on a slide)
Rosalind Franklin
Name the 3 proposed mechanisms for DNA replication
a) Semiconservative mechanism: 1 parental strand and one newly made daughter strand
b) Conservative mechanism: 2 new daughter strands
c) Dispersive mechanism: segments of new DNA are interspersed with the parental DNA
Which mechanism for DNA replication is accurate?
Semiconservative model
Which two scientists performed an experiment to differentiate betweent the mechanisms
Stahl & Meselson
In DNA replication, 2 _______ strands separate and serve as template for synthesis of new strands. New nucleotides are added according to _____-__________ rules
Result is 2 ________ helices, and each double helix has _____ parental strand and ______ newly made daughter strand.
In DNA replication, 2 PARENTAL strands separate and serve as template for synthesis of new strands. New nucleotides are added according to BASE-PAIRING rules
Result is 2 DOUBLE helices, and each double helix has ONE parental strand and ONE newly made daughter strand.
How is DNA replication different in bacteria vs. in eukaryotes?
Bacteria - single origin of replication (think circle)
Eukaryotes - multiple origins of replication
What protein is the "unzipper" or the protein that moves in opposite directions to separate the 2 DNA strands?
DNA helicase
What protein alleviates the super coils (created by the replication fork during unwinding)?
DNA topoisomerase
Which protein synthesizes DNA
DNA polymerase
T/F, DNA polymerase can only add a new nucleotide to the 3’-OH of an existing nucleotide
TRUE, has two consequences:
- Cannot begin DNA synthesis on a bare template strand
- DNA synthesis always proceeds in a 5’ to 3’ direction
What is DNA primer
- initiates DNA synthesis by making a short segment of DNA (called RNA primer)
T/F, the new daughter strand must be synthesized ANTIPARALLEL to its template
= true
DIfferentiate between Leading and Lagging strands
Leading strand:
- a single RNA primer is made
- synthesis of DNA is continuous from the primer, making one long molecule
- synthesis occurs in SAME direction as fork movement
Lagging strand:
- synthesis occurs in OPPOSITE direction to fork movement
- requires multiple RNA primers
- SHORT segments of DNA are synthesized
What is the name for the short segments of DNA that are eventually connected?
Okazaki fragments
what is the role of DNA ligase in DNA synthesis?
DNA ligase = connects the newly synthesized DNA to the other parts of DNA -> used to seal DNA fragments of lagging strand
T/F, the active site of DNA polymerase is unlikely to form bonds if pairs mismatched
TRUE
T/F, DNA polymerase has PROOFREADING activity
TRUE
Gene Expression?
process by which the information of a gene is made into a functional product
Mutation?
a heritable change in the genetic material - can alter gene sequence
What did Archibald Garrod study patients of?
Archibald Garrod studied patients with metabolic defects such as alkaptonuria (black skin, cartilage, urine)
Define Inborn Errors of Metabolism:
a group of rare genetic disorders that affect the body's ability to convert food into energy:
What did Beadle and Tatum study and discover
- studied common bread mold
- they had a ONE GENE ONE ENZYME theory
- discovered that enzymes are only one category of cellular proteins -> genes encode for other types
- some proteins are composed of two or more polypeptides
Who proposed the Central Dogma of Gene Expression?
Watson & Crick
Give some differences between Prokaryotes and Eukaryotes
Prokaryotes:
- no nucleus
- smaller
- DNA in cytoplasm
Eukaryotes:
- has nucleus
- more complex
- bigger
- DNA in nucleus
What is a gene:
an organized unit of DNA sequences
- transcribed into RNA
- results in the formation of a functional product
What does tRNA and rRNA stand for
tRNA = transfer RNA
rRNA = ribosomal RNA
Define Promoter, Terminator, Transcribed region and Regulatory sequence
Promoter: section that brings in RNA polymerase to start the transcription - signals the beginning of transcription
Terminator: boots RNA polymerase off - signals the end of transcription
Regulatory sequence: site for binding of regulatory proteins
- can increase/decrease the rate of transcription
Transcribed region: this region contains the info that specifies an amino acid sequence
T/F, RNA doesn't contain T, it contains U(uracil) instead
TRUE
Name the three stages of transcription:
1. Initiation
2. Elongation/synthesis of the RNA transcript
3. Termination
Define template/noncoding strand and coding strand
Template/noncoding strand: the DNA strand used as a template for RNA synthesis
Coding strand: DNA strand NOT used for transcription
- Unlike DNA polymerase:
- RNA polymerases can start on a template _______________ (but still uses 3' OH to link the strands)
- RNA polymerases _________ proofread and have no exonuclease activity
- Unlike DNA polymerase:
- RNA polymerases can start on a template WITHOUT A PRIMER (but still uses 3' OH to link the strands)
- RNA polymerases DO NOT proofread and have no exonuclease activity
What are the 3 processes of RNA processing?
Capping: a different nucleotide gets added to the 5' end (as soon as RNA starts coming out) = 5' cap (protects mRNA)
Tailing: increases mRNA stability, aids in export from nucleus = poly A tail
Splicing: removing introns from the transcript and joins exons together
What catalyzes splicing?
- catalyzed by the spliceosome
What are snRNPs
snRNPs form the core of the spliceosome
- are made of snRNA & proteins
What are the three parts to ribosome structure?
1. A site = aminoacyl site
2. P site = peptidyl site
3. E site = exit site
APE = the direction that the tRNA goes in when translation occus
Why is the plasma membrane important and what is it:
Biomembrane that separates the internal contents of a cell from its external environment
- Regulates the traffic of substances into and out of the cell
- Provides an interface to carry out many vital cellular activities
The plasma membrane is a __________ of lipid, protein, and carbohydrate.
Plasma membrane is a MOSAIC of lipid, protein, and carbohydrate.
List the three types of membrane proteins:
1. Transmembrane proteins
2. Lipid-anchored proteins
3. Peripheral membrane proteins
Name the three influences on membrane fluidity
1. Length of phospholipid tails (shorter vs. longer can affect the stiffness of the membrane)
2. Double bonds in phospholipid tails
3. Presence of cholesterol (can increase and decrease fluidity)
Shorter lipid tails interact _____ with each other, making the membrane ______ fluid.
Shorter lipid tails interact LESS with each other, making the membrane MORE fluid.
Double bonds create _______ in the lipid tails = unsaturated fatty acids
This _________ interactions between adjacent tails, making bilayer ______ fluid.
Double bonds create KINKS in the lipid tails = unsaturated fatty acids
This REDUCES interactions between adjacent tails, making bilayer MORE fluid
Cholesterol and Fluidity:
• Tends to stabilize membranes
• Effect depends on temperature
• At higher temperatures, cholesterol makes membrane ____ fluid
• At lower temperatures, cholesterol makes membrane ______ fluid
At higher temperatures, cholesterol makes membrane LESS fluid (liquid is disordered)
• At lower temperatures, cholesterol makes membrane MORE fluid (liquid is ordered)
Osmosis
movement of water across membranes in response to solute concentration gradients
- helpful when the solute cannot cross membrane to reach equilibrium so the water will move
Crenation = ?
Lysis = ?
Crenation = cell shrinkage
Lysis = cell swelling
T/F, transporters are slower than channels
TRUE, channels are very quick
What are the three kinds of transporters
1. Uniporters - single ion/molecule transported
- ONE DIRECTION
2. Symporters - two or more diff types transported
- BOTH IN SAME DIRECTION
3. Antiporters - two or more diff types transported
- OPPOSITE DIRECTIONS (one in, one out)
Transporters that uses energy sources to change conformation are also called ________.
Transporters that uses energy sources to change conformation are also called PUMPS.
Out of primary active transport and secondary active transport, which one uses pre-existing gradient to drive the active transport and which one uses direct energy to transport the solutes?
Direct energy = primary active transport
Pre-existing gradient = secondary active transport
A Na+/K+ pump is what type of pump
an electrogenic pump
- generates an electrical gradient
- net export of 1 positive charge (3 out 2 in)