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Week 2
Intro to genetics, mitosis + meiosis
| Question | Answer |
|---|---|
| Define heredity | the passing down of genetic information from parent to offspring through genes |
| Describe the role of chromosomes + genes in heredity | Chromosomes are a long double helix of DNA wrapped around proteins called histones, + they store genetic info; genes are segments of DNA that carry the genetic info for specific traits |
| Describe structure + arrangement of chromosomes in a cell | Reside in the nucleus of eukaryotic cells as chromatin (loosely packed) condenses into chromosomes during cell division |
| Somatic cell vs. gamete | somatic cells: diploid (2n), body cells, formed during mitosis gamete: haploid (n) sex cells, formed during meiosis |
| Define homologous chromosomes | Chromosomes of the same type/pair (in diploid organisms) one from mother/one from father, may carry different alleles |
| Define diploid cell | contains 2 complete sets of chromosomes (one from each parent) that form homologous pairs |
| Define haploid cell | a single complete set of chromosomes |
| What is the diploid chromosome # for human body cells? | 46 chromosomes arranged in 23 pairs (22 pairs of autosomes and one pair of sex chromosomes) |
| Describe the structure of a duplicated chromosome | 2 sister chromotids are attached together in the middle at the centromere. (still = 1 chromosome) |
| mitosis vs. meiosis (# of stages, # of daughter cells produced + the ploidy of the daughter cells) | mitosis: 1 stage, 2 identical daughter cells, 2n diploid, somatic cells meiosis: 2 stages, 4 unique daughter cells, n haploid, germ/sex cells |
| mitosis vs. cytokinesis | Mitosis: division of the replicated chromosomes Cytokinesis: division of the cytoplasm |
| Describe the function of cell division in uni + multicellular organisms | uni: cell division acts as reproduction multi: growth + development, repair, maintence |
| Purine vs. pyrimidine | Purine: short name, bigger molecule (double ring) A + G Pyrimidine: longer name, smaller molecule (single ring) C + T/U |
| Describe structure + function of a nucleotide | consists of a nitrogenous base (A,T,C,G,U), a pentose sugar + a phosphate group. form into polynucleotides which become the backbone for DNA/RNA |
| Describe structure + function of DNA (in heredity) | Double helix molecule made of nucleotides that stores genetic information |
| RNA vs. DNA | DNA: double stranded, CGAT bases, deoxyribose sugar, stores long term genetic info (more stable) RNA: single stranded, CGAU bases, ribose sugar, carries out instructions for protein building with mRNA, tRNA + rRNA |
| Define central dogma | the flow of info in cells (DNA-info storage->transcription-> RNA-info carrier ->translation-> proteins-active cell machinery) |
| Chromosome vs. chromatin | chromatin: loose uncloiled DNA with histones in the nucleus, present during interphase chromosomes: condensed chromatin, present during mitosis. |
| Define mitosis + function | division of the cells nucleus into 2 identical diploid daughter cells; production of identical cells for growth + repair, asexual reproduction |
| Explain interphase (mitosis) | the phase before/after mitosis (cell division) cells spend most of their time in interphase; chromosomes are uncoiled; cells are growing + preparing for divisions/fullilling their specialized functions |
| Explain prophase (mitosis) | chromosomes condense; spindle aparatus begins to form; nuclear envelope breaks down + microtubules contact chromosomes at kinetochores |
| Explain metaphase (mitosis) | chromosomes complete migration to middle of cell |
| Explain anaphase (mitosis) | sister chromatids seperte into daughter chromosomes, which are pulled to opposite poles by the spindle aparatus |
| Explain telophase (mitosis) | nuclear envelope reforms; chromosomes de-condense cytokinesis then happens, splitting the cell into 2 |
| Describe the cell cycle + stages | 4 stages; G1, S, G2 + M |
| Explain significance of the S phase of the cell cycle | The DNA is copied/replicated during S phase, doubling the DNA content, ensuring that the daughter cell will recieve a full set of genetic information |
| Interphase vs. mitosis length | interphase takes up most of the cycle, around 90-96% of it |
| Cell cycle of differentiated vs. undifferentiated cells | differentiated cells (ones with specific functions enter G0 phase to focus on their functions) undifferentiated (stem, unspecialized cells) have rapid cell cycles |
| Importance of cell cycle checkpoints (what would happen if you lost them) | ensure that DNA is undamaged, cell size and nutrients are sufficient, + chromosomes have replicated correctly + are aligned right before division. without checkpoints could result in uncontrolled cell division + mutations + cell death etc |
| Cytokinesis in plant vs. animal cells | animal: ring of actin filaments called the contractile ring forms, pinching the cytoplasm, forming a cleavage to divide cell plant: vesicles bring cell wall/membrane components to middle of cell to form cell plate which then forms wall, dividing cell |
| (not a flashcard) be able to label + recognize all mitosis phases | |
| What events during interphase + mitosis ensure that the chromosome # is the same in the daughter + parent cell? | DNA is replicated during S phase/interphase + then is seperated exactly during mitosis to produce identical daughter cells |
| What are kinetochores? | proteins that assemble on the centromere of chromosomes during mitosis/meiosis. where the spindle aparatus attaches to the chromosomes |
| Kinetochore microtubules vs nonkinetochore microtubules | kinetochore: arranged in bundles; attatch directly to chromosomes non: dynamic; overlap to push spindle poles apart + do NOT attach to chromosomes |
| Cell division in prokaryotes vs. eukaryotes | prokaryotes: single circular strand of DNA; nucleoid; replicates by binary fission eukaryotes: linear chromosomes; nucleus; replicates by mitosis + cytokinesis |
| Bacterial chromosomes vs. eukaryotic chromosomes | bacteria: single strand of DNA, housed in nucleoid, circular, NO histones eukaryotic: multiple, linear, housed in the nucleus, histones |
| Describe process of binary fission in bacteria | chromosomes replicate; then are pushed apart by ParM proteins; ring of FitZ protein forms inbetween chromosomes, then constricts to seperate them (each daughter cell recieves one copy of the replicated parental DNA) |
| Why is it hypothesised that the process of binary fission gave rise to mitosis? | both produce 2 genetically identical daughter cells, and mitosis is essentially just a more complex version of binary fission |
| Why are dinoflagellates, diatoms + yeast "intermediates" betweeen bacterial binary fission + mitosis? | they preform a form of cell division thats "between" binary fission + mitosis |
| What 3 events need to happen for a cell to divide? | copying of the DNA seperating the copies dividing the cytoplasm to create the 2 complete cells |
| Chohesin function | ring shaped protein that holds sister chromatids together |
| Condensin function | ring shaped protein that condenses the DNA |
| Microtubule function | move chromosomes to the poles in cells |
| Spindle aparatus function | produces mechanical forces move replicated chromosomes in early mitosis + pull them apart in late mitosis. made of microtubules |
| Polar vs. astral vs. kinetochore microtubules | polar: extend from each spindle pole + overlap with eachother astral: anchor spindle poles in place kinetochore: attatch to the chromosomes |
| Define meiosis + function | division of the cell into 4 unique haploid daughter cells production of gametes or spores that are haploid + genetically different |
| What is the basis for matching of pairs of homologous chromosomes when preparing a karyotype? | they are ordered from biggest to smallest, and paired based on length, position of centromere, + banding |
| human female vs. male karyotype | the sex chromosomes differ (the 23rd pair) female: xx male: xy |
| Gamete vs. somatic cell chromosome # | gamete: haploid; 23 unpaired chromosomes somatic: diploid; 46 chromosomes (23 pairs) |
| Why does the seperation of homologous chromosomes in meiosis 1 result in increased variation in the haploid cells? | Each chromatid has a unique combination of the maternal + paternal chromosomes |
| Bivalent meaning | the structure that results from synapsis is called a bivalent (holds the 2 homolog pairs together) |
| Meiosis 1 vs. meiosis 2 | 1: seperates homologous chromosomes (diploid->haploid) into 2 cells; crossing over/pairing of homologous chromosomes; ploidy is halved 2: seperates sister chromatids resulting in 4 unique haploid cells; no crossing over; ploidy stays the same |
| Explain synapsis (meiosis 1) | sister chromatids are joined together by cohesions, homologs pair by synapsis + are held together by proteins called the synaptonemal complex; cross over occurs between non sister chromatids, complex dissassembles + homologs held only at chisasmata |
| DNA in chromosomes at end of meiosis 1 vs. end of meiosis 2 | 1: haploid cells, 23 replicated chromosomes 2. haploid cells, 23 UNreplicated chromatids |
| How do sister chromatids stay together in meiosis 1 but separate in meiosis 2/mitosis | proteins called cohesions |
| What processes during sexual reproduction account for the genetic variation in organisms | random fertilazation (any sperm can fuse with any egg) crossing over |
| Evolutionary significance/advantage of switch from asexual to sexual reproduction | only sexual reproduction results in shuffling of the alleles, resulting in genetic variation |
| Explain crossing over | produces recombinant chromosomes (combined genes from each parent) homologous portions of 2 non sister chromatids trade places; contributes to genetic variation (happens during prophase 1) |
| Describe the G1 phase (in the cell cycle) | interphase 1st gap phase; cell growth + protein content increase many regulatory proteins increase |
| Describe the S phase (in the cell cycle) | interphase synthesis phase; DNA replicates |
| Describe the G2 phase (in the cell cycle) | interphase 2nd gap phase; cell prepares for mitosis + cytokinesis |
| Describe the M phase (in the cell cycle) | Mitosis: parent cell divides into 2 identical daughter cells |
Created by:
every_august
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