PHOTOSYNTHESIS/RESPIRATION
Define:
· photosynthesis – using water and energy from the sun, carbon dioxide is turned into sugars and oxygen is released as a by-product
· cellular respiration – using oxygen, sugars are broken down and ATP (the cell’s energy currency) is produced
· metabolism – all of the reactions that occur in a living thing, necessary to maintain life
· autotrophs – make their own food, for example, by photosynthesis (plants, algae, etc.)
· heterotrophs – cannot make their own food and must consume other organisms (animals, fungi, etc.)
· glycolysis - breaks down glucose into 2 pyruvate, 2 ATP and NADH, occurs in all organisms before aerobic or anaerobic respiration/occurs in the cytoplasm
· alcoholic fermentation - occurs without oxygen (anaerobic), produces ethanol and carbon dioxide and regenerates NAD+ so that glycolysis can occur again, this process produces no ATP/occurs in the cytoplasm, occurs in unicellular organisms such as yeast and bacteria, used to produce alcoholic beverages
· lactic acid fermentation - occurs without oxygen (anaerobic), produces either lactic acid and regenerates NAD+ so that glycolysis can occur again, this process produces no ATP/occurs in the cytoplasm, occurs in unicellular organisms such as bacteria, can occur in mammal muscle cells deprived of oxygen (causes a temporary burning sensation during exercise)
1. Which organelle is the site of photosynthesis? chloroplast
2. Which organelle is the site of aerobic respiration? mitochondria
3. What do enzymes do? Enzymes speed up chemical reactions by lowering the amount of
energy that they need to proceed (activation energy).
4. Which wavelengths of light do green plants absorb best? Green plants absorb blue and red
light best, while reflecting green light.
5. Write overall equations for photosynthesis and aerobic cellular respiration? How are
these 2 equations related?
PHOTOSYNTHESIS: SUNLIGHT + 6H20 + 6CO2 ® C6H12O6 + 6O2
CELLULAR RESPIRATION: C6H12O6 + 6O2 ® 6H20 + 6CO2 + ATP
These processes depend on one another. Photosynthesis produces the glucose and oxygen
needed for cellular respiration and cellular respiration produces the carbon dioxide needed
for photosynthesis. These processes are an important part of the carbon-oxygen cycle.
CELL CYCLE
Define:
· cell cycle – the life cycle of a cell, including growth, DNA replication and division
· mitosis – nuclear division
· cytokinesis – division of cytoplasm (organelles and cytosol)
· interphase – phase of the cell cycle during which the cell performs its function(s) and prepares for division (G1, S and G2)
1. Draw and label a diagram illustrating the cell cycle.
2. What occurs during each phase of the cell cycle? (G1, G2, S, M and C)
G1 – cell grows and “does it’s job”
S – DNA is copied (DNA replication) in preparation for division
G2 – cell doubles the amount of cytosol and organelles in preparation for division
mitosis (M) – nucleus divides, resulting in 2 nuclei
cytokinesis (C) – division of cytosol and organelles, cell membrane divides forming 2
new cells
3. Draw and label a diagram that illustrates what occurs during each phase of mitosis.
(prophase. metaphase, anaphase, telophase)
MOLECULAR GENETICS AND PROTEIN SYNTHESIS
Define:
· replication – DNA is copied resulting in a new strand of DNA, this occurs prior to cell division
· translation – an mRNA molecule (copied from DNA) is read (translated) at a ribosome and a protein (or part of a protein-polypeptide) is made
· transcription – a segment of DNA is copied into an RNA molecule
· codon – 3 messenger RNA (mRNA) bases that code for a particular amino acid
1. Draw and label a segment of DNA including the following parts: deoxyribose (sugar), nitrogenous base (use at least one of each – adenine, guanine, cytosine and thymine), phosphate group
The “sides” of the DNA ladder are made up of deoxyribose molecules (sugar) and phosphate groups bound together, while the “rungs” of the ladder are made up of nitrogenous bases held together by hydrogen bonds. This ladder is twisted into a double-helix shape, similar to that of a spiral staircase.
2. How are DNA and RNA different?
COMPARE…. / DNA / RNAsugars / deoxyribose / ribose
nitrogenous bases / A, T, C, G / A, U, C, G (no thymine)
structure / double-stranded/double-helix / single-stranded
size / very long / very short (a copy of 1 gene)
location / cannot leave nucleus / made in nucleus but can move out of nucleus (goes to ribosome)
3. What is made when a gene is translated? protein
4. What do proteins do? Why are they important?
Proteins function in a variety of ways and are involved in nearly all cell processes. Protein
jobs include:
· enzymes – speed up chemical reactions
· antibodies – part of the immune system, help destroy foreign substances
· muscle contraction – responsible for movement
· hormones – regulate body functions
· structural support – constituent of body structures such as skin, hair, nails, muscles, internal organs
· transport – move substances around the body
5. Which organelle is the site of protein synthesis? ribosome
6. What is the structure of a DNA molecule (include all parts)? sorry…repeat question – see #1 in this section
7. What did Watson and Crick contribute to DNA discovery? Watson and Crick used research and data from other scientists to determine the structure of DNA. In 1953 they constructed a 3-D model of this structure.
8. What are the rules of base paring? Adenine only pairs with thymine, with a double bond between the two molecules. Cytosine only pairs with guanine, with a triple bond between the two molecules. (SEE DIAGRAM ABOVE – question #1).
9. How is mRNA produced? Enzymes split the section of DNA to be copied and mRNA is formed when one side of the spilt DNA molecule is “copied”. This copy is actually a segment of complementary bases. When the copying is complete the two sides of the DNA molecule reattach. This process is called transcription.
10. What does tRNA do (transfer RNA)? Transfer RNA carries an amino acid and transfers
this amino acid when its anticodon complements an mRNA codon. The amino acid is
released from the tRNA molecule and
becomes part of the protein being constructed at the ribosome.
11. What does mRNA do (messenger RNA)? How is it made? Messenger RNA is a copy of a
segment of DNA that is able to leave the nucleus and bring this information to a ribosome
where proteins are made. This copying process is necessary since DNA must stay
protected within the nucleus. (See description above for “How is it made?”).
12. What does gene expression mean? Genes are expressed or “turned on” when a protein is
made. Genes are only expressed when a particular protein is needed. For example, some
genes are used only during development and are then “turned off” (or not expressed
again) after the organism is has developed.
13. Create your own DNA sequence and then transcribe (into mRNA) and translate (into a
protein) this sequence.
DNA A C C T G C A A C G C C A A T
mRNA U G G A C G U U G C G G U U A (remember…in RNA there is no thymine,
but uracil instead)
protein trp – thr – leu – arg - leu (below is the chart used to find amino
acids)
MEIOSIS AND SEXUAL REPRODUCTION
Define:
· sexual reproduction - gametes combine, genetic recombination occurs
· asexual reproduction - offspring are produced by only one parent, clones are produced by mitosis no genetic recombination occurs
· clone - cells or entire organisms produced by mitosis, genetically identical to parent
· haploid (n)– each cell contains one set of chromosomes, not pairs
· diploid (2n) – each cell contains (homologous) pairs of chromosomes
· homologous chromosomes – a pair of chromosomes similar in size, shape and the genetic information they contain, one is inherited from each parent
1. What kinds of cells undergo meiosis? sex cells (gametes, germ cells, egg and sperm)
2. Which sex chromosomes do females have? XX Which sex chromosomes do males have? XY
3. What is a karyotype? What information can be obtained by examining a karyotype? What do doctors and scientists use karyotypes for? A karyotype is a picture of a person’s chromosomes, paired and organized according to size. A karyotype is used to determine the sex of an unborn child as well as if there are any chromosomal abnormalities, such as extra or missing chromosomes or pieces of chromosomes. Doctors and scientists used this information to counsel and prepare parents as well as for research.
4. What is crossing-over? Why is it important? Crossing-over is an exchange of genetic material that occurs during prophase I of meiosis. Crossing-over is important because it results in genetically different offspring (genetic variation).
MENDELIAN GENETICS
Define:
· allele – alternate forms of a gene
· homozygous – alleles are the same (for example, BB or bb)
· heterozygous – alleles are different (for example, Bb)
· genotype – the genetic makeup of an organism (the “letter codes”)
· phenotype – the physical appearance of an organism
· heredity – the passing of traits from parent to offspring
· dominant – masks the other (recessive) allele, the phenotype is expressed when paired with a recessive allele
· recessive – masked by the dominant allele, phenotype is masked when paired with a dominant allele
1. Who is considered the father of genetics? Gregor Mendel
2. How many alleles does each offspring receive? Two – one allele from each parent.
3. How is a Punnett square used to predict the outcome of a genetic cross? A Punnett square
identifies all of the possible allele combinations (of a particular trait) when two organisms
are crossed.
4. Create your own Punnett square problem. Indicate which trait is dominant and which is
recessive so that a classmate can solve your problem. Indicate the genotypes and
phenotypes that result from your cross.
Brown eyes are dominant over blue eyes. Cross two heterozygous individuals.
B=brown/b=blue
B b
BB / BbBb / bb
B
b
resulting genotypes – 1 BB: 2Bb: 1bb
resulting phenotypes – 3 brown eyes: 1 blue eyes
5. What is a dihybrid cross? What phonotypic ratio is expected when two individuals
heterozygous for both traits are crossed? A dihybrid cross is used to cross two different
traits simultaneously, for example, body color and number of eyes (see diagram below).
When crossing organisms heterozygous for both traits the expected phenotypic ratio is - 9
both dominant traits: 3 one dominant/one recessive: 3 one dominant/one recessive: 1 both
recessive traits. In the example above with green color dominant over purple color and two
eyes dominant over one, the phenotypic ratio is 9 green color/two eyes: 3 purple color/two
eyes: 3 green color/one eye: 1 purple color/one eye.
6. What is incomplete dominance? Incomplete dominance occurs when one allele is not
completely dominant over another and a blending of traits occur. For example, crossing red
Japanese four o’clock flowers with white Japanese four o’clock flowers the result is pink four
o’clock flowers.
7. What is a sex-linked trait? What are some examples of sex-linked traits? A sex-linked trait
is a trait whose gene is found on one of the sex chromosomes (only X-linked traits were
discussed in class). Examples of X-linked traits include hemophilia, color blindness and
Duchene muscular dystrophy.
8. How are Punnett squares used to predict the inheritance of sex-linked disorders? Punnett
squares for sex-linked traits indicate both the sex of the individual and the alleles the
individual receives.
9. Solve the following genetic word problem: In humans colorblindness is a sex-linked
recessive disease. If a man with normal vision marries a woman that is heterozygous for
colorblindness, what possible genotypes and phenotypes would result?
N=normal vision
n=colorblindness
XN Xn
XN XN / XN XnXN Y / XnY
XN
Y
10. What is a pedigree? How can pedigree analysis trace the inheritance of a particular trait?
A pedigree is used to trace the history of a particular trait in a family. A pedigree can be
used to predict the inheritance of a trait or the chance that the trait will be passed on.
GENES AND CHROMOSOMES
Define:
· mutation – any change in DNA
· chromosomes - made up of coiled DNA, visible during cell division
· chromatin - uncoiled DNA that is visible when the cell is not dividing..
· chromatid – either side of a replicated chromosome
· centromere – holds sister chromatids together, chromosomes are made up of 2 sister chromatids
1. Do more complex organisms have more chromosomes? Explain your answer. Chromosome
number does not indicate the complexity of an organism, it is only representative of the
amount of genetic material needed to make up a particular organism.
2. What are the parts of a chromosome? centromere – holds sister chromatids together,
chromosomes are made up of 2 sister chromatids
3. How many chromosomes do humans have? 46 chromosomes, 23 pairs
4. What is the difference between chromatin and chromosomes? Chromatin is the uncoiled
DNA that is visible when the cell is not dividing. Chromosomes are made up of coiled
DNA and are visible during cell division.
5. What is the difference between a body cell mutation and a sex cell mutation? Body cell
mutations only affect the somatic cells of an organism (like skin or nerve cells) and are not