test 6 Flashcards
cell division and classical genetics
What is the central dogma of molecular biology?
theory that DNA stays in the nucleus but needs to direct activities into the cytoplasm, therefore it only flows in one direction, DNA is responsible for the building of proteins, Replication (DNA → DNA) -> Transcription (DNA → RNA) -> Translation (RNA → Protein)
What is DNA made of? Why is it important to life?
double helix shaped polymer, consists of nucleotide monomers with a sugar-phosphate backbone, important as it serves as the instructions for protein- building that supports life functions- develop, survive, reproduce
complimentary paired nucleotides
adenine (A) + thymine (T) and cytosine (C) + guanine (G)
what does a karyotype show
a display of the chromies of a cell, which can be used to identify chromie abnormalities
chromosome
condensed chromatin passed from parent to offspring
sister chromatid
a chromosome and its duplicate joined at the centromere
centromere
where sister chromatids link together
karyotype + down syndrome
third chromie is present in one of the 23 homologous pairs, making 47 total chromies
cell cycle
interphase (90%) and mitosis + cytokinesis (~10%)
stages of mitosis- nuclear division
- interphase 2. prophase 3. metaphase 4. anaphase 5. telophase 6. cytokinesis
interphase
centriole pair replicates & DNA replicates to create duplicated chromies, starts w/ 4 chromies + 8 tids
interphase stages
G1= growth 1 (centriole pair replicates, S= synthesis (DNA replicates), G2= growth 2 (nuclear membrane + nucleolus still intact)
prophase
centriole pairs begins to migrate to opposite poles, nuclear membrane begins to dissolve, spindle fibers begin to form between centriole pairs, duplicated chromosomes begin to condense, nucleolus begins to disappear
metaphase
centriole pairs are fully migrated to opposite poles, spindle apparatus (mitotic spindle) is fully formed, chromies in middle of cell, nuclear membrane dissolved, chromies most condense
anaphase
away, spindle fibers pull the sister chromatids apart at the centromere and drag them to opposite poles, cell elongates (ovoid-egg shaped)
telophase
pinching in (cleavage furrow), nuclear membranes begin to reform, spindle apparatus disassembled, chromies begin to decondense, nucleolus begins to reform
cytokinesis
2 daughter cells- 4 chromies each 0 tids, no spindle fibers, chromies decondensed + lengthened, nucleolus & nuclear membrane formed
what is the purpose of each cell checkpoint? what is checked?
to determine if the cell can continue, contents of cell are reviewed to assess for DNA damage or phase being incomplete
how does a cancer cell differ from a healthy cell
cancer cells do not regulate the cell cycle like normal, they divide excessively and invade other tissues of the body
What is the difference between a proto-oncogene and a tumor suppressor gene?
A proto-oncogene is a normal gene that can turn into an oncogene, which promotes cell growth. A tumor suppressor gene is a normal gene that inhibits cell growth and division, preventing cancer development
how does the cell prepare for mitosis/meiosis
they begin with diploid parent cells & chromies that were duplicated during the S phase of interphase (chromies duplicated)
what is the fxn of mitosis for a cell and where does it occur
produces 2 genetically identical diploid somatic daughter cells from somatic (body) cells, bone marrow, neurons, rbc, skin cells, 46 chromies
How does this process of cytokinesis differ in animal and plant cells?
in animals it creates a cleavage furrow- contracting microfilaments pinch the cell in 2, in plants the stiff cell wall prevents contraction & has a cell plate
How would you describe/depict the stages of mitosis?
interphase- normal, prophase- +spindle fibers,breaking NM + nucleolus, condensing chromies, metaphase-middle, everything lined up & touching, anaphase-away, chromatids moving, telophase- pinching in, things start to reform, cytokinesis- daughter cells, no tids
Why does cell division remain important even after an organism is fully developed?
cells weak out/die + need to be replaced (skin, digestive tract, broken bone)
What is the function of meiosis? Where does meiosis take place?
produces 4 genetically unique haploid gametic cells from germ cells (gametes), takes place in ovaries/testes (egg + sperm), 23 chromies
germ cell
biological cell that gives rise to gametes, 46 chromies
mitosis
diploid somatic cell, repairs esophageal cells, 2 daughters, genetically identical, 46 chromies
meiosis
produces haploid, pairs w/ homo chromies side by side on midline eQ, cytokinesis x2, crossing over, 4 daughters, ova + sperm, genetically unique, zygote, produce 23 chromies
zygote
diploid cell formed when a sperm fertilizes an egg
diploid cell
2 sets of homologous chromies (aka somatic cells) (2n), 1 from each parent, ex: germ + somatic
haploid cell
single set of chromies (from 1 individual) (aka gametes) (n)
What role does crossing over play in meiosis?
creates gametes that contain new combos of genes- genetic diversity
What is nondisjunction during meiosis? How can you tell from a karyotype that a person has a trisomy, such as in Down Syndrome?
failure of homo chromies to segregate properly during anaphase 1 to opposite poles resulting in gametes with an improper chromie complement– can tell because one chromosome has 3 chromatids instead of 2
How did Gregor Mendel contribute to our understanding of genetics?
studied pea plants, developed laws of inheritance
What does it mean for a plant to be true-breeding?
a plant that always produces offspring of the same phenotype when self-fertilized
What were Mendel’s hypotheses?
What is the Law of Segregation?
for any particular trait, the pair of alleles of each parent separate and only one allele from each parents passes to an offspring
Mendel’s law of independent assortment
during gamete formation, the idea that the allele a gamete receives for one gene does not influence the allele received for another gene
What is the difference between a dominant and recessive allele?
dominant allele is always seen phenotypically while recessive is only seen in homozygous state
How can a Punnett square be used in predicting the probable offspring of a one-factor cross? A two-factor cross?
genotype & genotypic ratio
specific combination of alleles for a given gene, ratio is comparison of genetic info
phenotype & phenotypic ratio
physical manifestation of an organism’s allellic combination, ratio is the comparison of phenotypes
What are the results of a cross when genes exhibit incomplete dominance? Codominance? Multiple alleles? Sex-linked inheritance?
What fruit fly traits and genetic crosses did you observe? How did they differ in each generation?
How are male and female flies identified for genetic mating?
What is measured by the chi-square test? How is it conducted and analyzed?
what is represented by degrees of freedom
check all the vocab
gamete
male and female sex cells – sperm and eggs
heterozygous
genotypes with 2 different alleles
homozygous
genotypes with 2 of the same alleles
recessive
allele that is expressed only in the homozygous state
dominant
allele that is always expressed
alleles
different forms of genes for a single trait
