BIOL 1100 Exam 03 study guide Flashcards
autotroph
producer”; can produce its own food, typically through photosynthesis
chemoautotroph
uses energy from inorganic compounds to make food; organism that can build organic molecules using energy derived from inorganic chemicals instead of sunlight
ex: thermophilic bacteria, sulfur-oxidizing bacteria, nitrogen-fixing bacteria and iron-oxidizing bacteria
photoautotroph:
uses sunlight to make food
* algae, plants, cyanobacteria
o heterotrophs
: “consumer”; must consume other organisms to obtain food; cannot make its own food
humans, animals
endosymbiosis
o idea that mitochondria and chloroplasts were once bacteria cells that were engulfed by a larger cell and they began living symbiotically
they both have own DNA different than nuclear DNA
Have two membranes
About the size of bacteria cells
reproduce similar way as bacteria
o stomata
(singular: stoma) small pores on the leaf underside that allows for gas exchange
“guard cells” specialized cells surrounding each stoma; responsible for actively opening and closing the pore to regulate gas exchange and H2O loss through transpiration
Stomata are the openings, guard cells control the opening and closing of those opening [sphincters]
Stomata are regulated by guard cells
the reaction of photosynthesis (the reactants and the products)
o Reactants: CO2 and H2O
o Products: Sugar and O2
o Photosynthesis Equation
6CO2 + 6H2O —-sunlightC6H12O6 + 6O2
Redox reactions in photosynthesis
o Electron Transfer in Photosynthesis: REDOX REACTION
Within the chloroplasts of plants, photosystems I and II act as light-absorbing complexes that capture light energy and use it to excite electrons from water molecules. These excited electrons are then transferred through a series of electron carriers within the thylakoid membrane, constituting a redox reaction.
o Reduction of NADP+: REDOX REACTION
At the end of the electron transport chain in photosystem I, the electrons are used to reduce NADP+ (nicotinamide adenine dinucleotide phosphate) to NADPH, a crucial energy carrier for the Calvin cycle.
Oxidation rxn photosynthesis
o Oxidation of Water: OXIDATION REACTION
When light strikes the photosystem II, water molecules are split, releasing oxygen as a byproduct while donating electrons that are transferred along the ETC. This process is considered an oxidation reaction as water loses electrons.
where the light reactions occur
thylakoid membranes of chloroplast
where the Calvin cycle occurs
occurs in the stroma of chloroplasts
what happens overall in light reactions
converts light energy to chemical energy
makes ATP and NADPH (an e- carrier)
What happens overall in calvin cycle
uses ATP and NADPH
makes sugar (food)
the sites of light absorption
o Light harvesting complex of PSI and PSII
- Know the main pigments of thylakoid membranes and their colors
o chlorophylls: chlorophyll a and chlorophyll b; green
o carotenoids: B-carotene, orange
- Why do we see plants as the color green
o green wavelengths are reflected
- What color contributes the least amount of energy to photosynthesis
green
o Interphase (what events occur)
G1, S, G2– normal growth and preparation for cell division
g1 (phase; occurs)
Interphase
change is not evident but cell is biochemically active
s phase
when DNA synthesis occurs
* all chromosomes are replicated, and the copies are paired as sister chromatids
o sister chromatids: 2 identical copies of chromosomes connected at the centromere
* ID copies of DNA molecules (sister chromatids) are joined at the centromere
* Centrosomes produce mitotic spindles to move the chromosomes (across cell to poles)
o in animal cells, associated with centrioles which help organize cell division
g2 (second gap
- energy is replenished
- organelles reproduce
- cytoskeleton breaks down
o Karyokinesis/Mitosis (phases; overall occurance)
(PPMAT)– replicated DNA and cytoplasm are split and the cell divides
prophase
- nuclear envelope breaks down
- Membranous organelles (eg. Golgi complex, endoplasmic reticulum) disperse toward edges of the cell
- The nucleolus disappears
- Centrosomes begin migration to poles
- Microtubules of the spindle form
- Sister chromatids coil tighter (aided by condensin proteins)
Prometaphase
- Sister chromatids develop a protein kinetochore in the centromere region which attaches the chromatids to the spindle microtubules
Metaphase
- Chromosomes line up along metaphase plate
- Sister chromatids remain attached by cohesion proteins
Anaphase
- Cohesin proteins degenerate allowing chromatids to separate
- Separated sister chromatids move in opposite directions toward the centrosomes to which their microtubules are attached
- The cell elongates
Telophase
- Chromosomes reach opposite poles and begin to decondense (unravel)
- Spindles depolymerize into tubulin monomers that will form cytoskeletal components for the daughter cells
- Nuclear envelopes form around the chromosomes, and nucleosomes appear within the nuclear area
o Cytokinesis
– cytoplasmic components physically separate into 2 daughter cells
difference between somatic cells and gametes, what each is produced by, and be able to define and know which type of cell is haploid and diploid
o somatic cells: body cells; diploid (2n); produced by mitosis (2 identical daughter cells cells); no diversity; example skin cells
o gametes: sperm and egg; haploid cells (1n); produced by meiosis (results in haploid gametes which carry half the # of chromosomes as parent cell)
cell cycle checkpoints (names; when)
o G1 Checkpoint (occurs at the end of G1)
o G2 Checkpoint (occurs at the G2 to Mitosis transition)
o M Checkpoint (occurs in metaphase of mitosis)
g1 checkpoint (purpose; what happens)
determines whether all conditions are favorable for cell division: adequare cell reserves and size; ext. influences
check for genomic DNA damage
must meet all requirements to be allowed to enter S phase
* can stop cycele and try to fix problem or
* enter G0 and wait for signs that conditions are better
M checkpoint (purpose; what happens)
occurs near end of metaphase (during mitotic phase)
determines whether all sister chromatids are correctly attached to to the spindle microtubules “spindle checkpoint”
cycle will not proceed until kinetochores of each pair of sister chromatids are firmly anchored to at least two spindle fibers
* failure to correct –> non-disjunction of chromatids
- What type of cells in the human body are in a permanent state of non-division (G0)
o Permanent G0: brain and cardiac muscle cells; will never divide so can never heal
is the difference between a benign tumor and malignant tumor
o benign growth that is not cancerous and does not invade nearby tissue or spread
o malignant growth that is uncontrolled cancerous cells that can spread to nearby tissues or through body
chromosome count for normal human body cells and gametes
o Human somatic cells: 23 pairs of chromosomes (46 total)
Somatic cell: the diploid (2n) body cells of an organism
o Human gamete: 23 chromosomes
Gamete: the haploid (1n) sex cells of a sexually reproducing organism
Sperm and egg; They combine at fertilization to create the first diploid cell (called the zygote) containing 23 pairs, or 46 total chromosomes
- Compare and contrast mitosis and meiosis
o Both
Divide the nucleus in eukaryotic cells
o Mitosis
Single division
No homologous pairing/no tetrads
Produces genetically identical clones
Does not reduce ploidy
o Meiosis
Two divisions
Homologous chromosomes pair to form tetrads
Genetic variation due to crossing over and random assortment in anaphase I
Reduces ploidy (2n –> 1n)
o Sexual reproduction
combines cells (gametes) from 2 parents through fertilization
By mixing chromosomes from two individuals genetic diversity is increased
Requires meiosis, which starts with 1 diploid reproductive germ-line cells and produces 4 haploid gametes that are genetically unique
o Homologous chromosomes
: the pair (one from mother and one from father) of chromosomes that carry the genes for the same characteristics at the same location
This is not the same thing as sister chromatids
o Asexual reproduction
involves only one parent, therefore the offspring are genetically identical to the parent cell. Examples: mitosis, binary fission, budding
o Sister chromatids
made through S phase chromosome replication; identical and attach at the centromere
o Gamete
: the haploid (1n) sex cells of a sexually reproducing organism
o Zygote
a fertilized egg (embryo) the first diploid cell in an organism 23 pairs or 46 chromosomes
o Crossing-over
Segments of chromosomes can be exchanged
at the end of meiosis, no two cells are identical.
o Nondisjunction
failure of synapsed homologs to completely separate and migrate to separate poles during the meiosis’ first cell division; occurs when homologous chromosomes or sister chrmoatids fail to separate during meiosis, resulting in an abnormal chromosome number; may occur during meiosis I or meiosis II
o True-breeding:
when an organism is homozygous for a trait and can only produce offspring with the same trait
meaning they only produced offspring with their phenotype (mendel’s peas)
o Hybrid
the offspring produced by two parents that were true breeding for different phenotypes. The offspring is heterozygous.
Mendel used true breeding parents to create hybrids
Monohybrid – an organism that is heterozygous (hybrid) for one trait
Monohybrid Crosses – the mating or crossing of two monohybrids
o Carrier
an individual who possesses one copy of a mutated gene associated with a disease, but does not exhibit symptoms themselves because the mutation is recessive; they can still pass this mutated gene on to their offspring, who may develop the disease if they inherit the mutated gene from both parents
o Linked-genes
genes carried on the same chromosome
They are called “linked” because they are usually inherited together — if the offspring gets one of the genes then they are highly likely to get the other, almost as if the two genes were tied together. For example, blonde hair and blue eyes
However, we know that even linked genes can be inherited separately because of cross-over
The distance between linked genes determines how likely they are to be inherited separately
Genes that are farther apart on the chromosomes are more likely to separate during cross-over
o Sex-linked genes
genes located on the sex chromosomes (X and Y in humans)
o Complete dominance
alleles that mask others – often designated with capital letters. Example: P for purple flower
o Incomplete dominance
: when the dominant allele does completely hide the recessive allele, resulting in hybrid offspring being a blend between the dominant and recessive phenotype.
o Codominance
when there is more than one allele that is dominant.
If an organism inherits two codominant alleles, they both get expressed.
An example of codominance is human blood types: Both type A and type B alleles are dominant to type O, so if a person type A from one parent and type B from the other parent, both alleles will be expressed and the offspring will be type AB blood.
o Pleiotropy
occurs when alleles code for more than one trait. For example, the tail-less allele in Manx cats codes for embryonic development of no tail (or very short tail) and also vital metabolic functions
In humans, the gene for Sickle Cell Anemia is a pleiotropic gene.
A single gene codes for the formation of hemoglobin in the red blood cells, sickle cell results from the gene coding for ONE wrong amino acid in the protein sequence of the hemoglobin.
This one gene mutation also causes other health problems, such as organ damage/failure, stroke, ulcers and retinopathy
o Polygenic inheritance
there are many genes that all add up to create the overall phenotype of the organism.
In humans, skin color, hair color, eye color, and height are all examples of polygenic inheritance
We inherit many genes for each of these characteristics and they all all add to give us our characteristics. This is why we have a wide range of skin colors, hair colors, eye colors and heights.
- What type of inheritance in sickle cell
o Pleiotropic gene; autosomal recessive: must inherit 2 copies of the mutated gene, one from each parent
alleles and where they are located
o Allele: specific versions of a “hereditary particle” (today = versions of a gene)
o Location: on chromosomes, specifically at the same position on a chromosome called the genetic locus
- Explain Mendel’s typical experiment
o Mendel crossed parent plants that differed in one trait to produce hybrid strains in order to see if what was inherited could be detected
- Explain Mendel’s Law of Independent Assortment and the phenotypic ratio resulting from a dihybrid cross that led him to it
o the alleles of a pair assort independently of other allele pairs during gamete formation
o If you count for each trait individually you will see each still gives a 3:1 ratio as in monohybrid crosses. This led Mendel to conclude that traits were inherited independently from one another
o Autosome
any chromosome that is not a sex chromosome; control the inheritance of all an organism’s characteristics except the sex-linked ones
o Sex chromosomes
the chromosomes the determine the sex of the organism (for humans, it is the 23rd pair)
- What determines the overall phenotype of an individual
o their genotype
- What is the genotype of human male and a human female
o 23rd pair xy/xx
- What is a karyotype, how is it done, what is the purpose of it
o an image of an organisms set of chromosomes
o – a type of genetic test that analyzes the size, shape, and number of chromosomes in a sample of cells taken from blood, amniotic fluid, bone marrow, or other tissue
o which is obtained by taking a picture of the chromosomes from a cell and arranging them in pairs according to size and banding patterns
o Changes in the number or structure of chromosomes may be a sign of a birth defect or genetic disease or condition, such as Down syndrome, Klinefelter syndrome, or Turner syndrome
Down’s syndrome
o a genetic disorder caused by nondisjunction of chromosome #21 (AKA: Trisomy 21)
- How many pairs of autosomes
22
o Chorionic Villus Sampling
can detect significant chromosomal differences, such as those that cause Down syndrome, spina bifida, cystic fibrosis as well as extra or missing pieces of chromosomes, some of which are associated with certain conditions
A provider inserts a needle or catheter through the cervix to remove a tiny sample of the placenta
A major advantage of CVS is that it’s performed much earlier in pregnancy, at 10 to 13 weeks and results obtained sooner (hours or days)
o Amniocentesis:
: prenatal test that can diagnose genetic disorders (such as Down syndrome and spina bifida) and other health issues in a fetus
A provider uses a needle to remove a small amount of amniotic fluid from inside your uterus, and then a lab tests the sample for specific conditions
can be done around 14-16 weeks and results can take weeks to get back
- What is the aim of cancer chemotherapy drugs
o to stop the cell division process by preventing any part of the cell cycle from progressing through the cell division process
g2 checkpoint (purpose; what happens)
prevents entry into the mitotic phase if conditions are not met: cell size and protein reserves checked
most important role: ensure all chromosomes have been replicated and undamaged
if problems detected, cell cycle stops to complete or repair
difference in cytokinesis of animal cells and plant cells
o animal cells divide by forming a “cleavage furrow” that pinches the cell membrane inward, while plant cells construct a new cell wall called a “cell plate” from the inside out, due to the presence of a rigid cell wall in plant cells which prevents them from pinching like animal cells do
Animal cleavage furrow
* A contractile ring made of actin filaments forms around the cell equator, constricting the cell membrane inwards to split the cell into two
Plant cell plate
* Vesicles derived from the Golgi apparatus fuse at the cell center, forming a new cell wall structure called the cell plate which gradually extends outwards to divide the cell
the final electron acceptor of the light reaction and what it yields
o FINAL ACCEPTOR: NADP+
o YIELDS: NADPH
relationship between chloroplast, thylakoid, grana, and mesophyll
o Chloroplasts contain: grana, which are stacks of thylakoids
o mesophyll: densely packed, columnar, elongated cells full of chloroplasts
o Lumen: inside thylakoids
o stroma the fluid inside the chloroplasts
o Mesophyll contain chloroplasts which contain grana which are stacks of thylakoids
