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Bio Ch. 8
| Question | Answer |
|---|---|
| Cell division | reproduction at the cellular level producing two identical daughter cells |
| Daughter cells | two genetically identical cells formed after division |
| Unicellular organism | uses cell division for reproduction of the species |
| Multicellular organism | uses cell division for growth repair and replacement |
| Asexual reproduction | one parent produces identical offspring with no variation |
| Sexual reproduction | two parents produce genetically varied offspring |
| Chromatin | uncoiled DNA and proteins in the nucleus |
| Chromosomes | condensed DNA structures containing genes |
| Gene | unit of DNA that controls a trait |
| Homologous chromosomes | chromosome pairs with same size shape and genes |
| Diploid (2n) | two sets of chromosomes (somatic cells) |
| Haploid (n) | one set of chromosomes (gametes) |
| Sister chromatids | identical copies of a chromosome after replication |
| Centromere | region holding sister chromatids together |
| Cell cycle | life cycle of a cell from formation to division |
| Interphase | growth and preparation stage (G1 S G2) |
| Mitotic phase | division stage including mitosis and cytokinesis |
| G1 phase | cell grows and duplicates organelles |
| S phase | DNA replication occurs forming sister chromatids |
| G2 phase | cell prepares for mitosis and reorganizes contents |
| Mitosis | division of nucleus producing identical genetic copies |
| Prophase | chromosomes condense nuclear membrane breaks down |
| Metaphase | chromosomes line up at cell equator spindle fibers attach |
| Anaphase | sister chromatids separate and move to opposite poles |
| Telophase | nuclear membranes reform chromosomes uncoil cytokinesis begins |
| Cytokinesis | division of cytoplasm into two cells |
| Animal cytokinesis | cell membrane pinches inward |
| Plant cytokinesis | cell plate forms between cells |
| Checkpoints | control points that regulate progression (G1 G2 M) |
| Internal signals | proteins and genes controlling cycle |
| External signals | environmental factors influencing division |
| Apoptosis | programmed cell death |
| Cancer | uncontrolled cell growth and division |
| Tumor | mass of abnormal cells |
| Benign tumor | non-spreading tumor |
| Malignant tumor | cancerous tumor that spreads |
| Metastasis | spread of cancer cells to other parts of body |
| Cancer cells immortal | divide indefinitely |
| Cancer cells undifferentiated | do not specialize |
| Cancer cells abnormal nuclei | irregular nucleus structure |
| Proto-oncogenes | normal genes that stimulate cell division |
| Oncogenes | mutated proto-oncogenes causing excessive division |
| Tumor suppressor genes | genes that stop cell division or repair DNA |
| Mutation | change in DNA sequence |
| Carcinogens | cancer-causing environmental agents |
| Inherited cancer | genetic mutations passed from parents |
| Surgery | removal of tumor |
| Radiation | kills cancer cells using high energy |
| Chemotherapy | drugs that target rapidly dividing cells |
| Personalized medicine | treatment tailored to individual genetics |
| Cancer cells vs normal cells | cancer cells divide uncontrollably ignore checkpoints and are immortal |
| How cancer spreads | through metastasis traveling via blood or lymph |
| Unicellular vs multicellular division | unicellular for reproduction multicellular for growth and repair |
| Cell cycle purpose | ensures growth DNA replication and proper division into identical cells |
| Purpose of each stage | G1 growth S DNA copy G2 prep M division |
| Mitosis definition and significance | produces identical cells for growth repair and genetic stability |
| Cells that undergo mitosis | somatic (body) cells |
| Purpose of prophase | condense DNA and break nuclear membrane |
| Purpose of metaphase | align chromosomes for equal separation |
| Purpose of anaphase | separate sister chromatids |
| Purpose of telophase | reform nuclei and finish division |
| Genetic continuity | identical genetic information passed to daughter cells |
| How mitosis ensures continuity | DNA replicated then evenly separated |
| Define cancer + characteristics | uncontrolled growth immortal abnormal undifferentiated forms tumors |
| Homologous pairs | chromosomes that contain the same genes, one from each parent |
| Autosomes | non-sex chromosomes; humans have 22 homologous pairs of autosomes |
| Sex chromosomes | chromosomes that determine biological sex (X and Y) |
| XX | female sex chromosome combination |
| XY | male sex chromosome combination; not fully homologous |
| Gametes | reproductive cells such as sperm and egg |
| Haploid (n) | cell containing one set of chromosomes |
| Diploid (2n) | cell containing two sets of chromosomes |
| Somatic cells | body cells that are not reproductive cells |
| Meiosis | type of cell division that produces haploid gametes from diploid cells |
| Fertilization | fusion of a haploid sperm and haploid egg to form a diploid zygote |
| Zygote | fertilized egg; first diploid cell of a new organism |
| Meiosis I | first division of meiosis that separates homologous chromosome pairs |
| Meiosis II | second division of meiosis that separates sister chromatids |
| Sister chromatids | identical copies of a chromosome attached at the centromere |
| Independent assortment | random alignment of homologous chromosome pairs during Metaphase I, increasing genetic variation |
| Crossing over | exchange of genetic material between non-sister chromatids during Prophase I |
| Non-sister chromatids | chromatids from homologous chromosomes that are not identical copies |
| Genetic variation | differences in DNA combinations among individuals |
| Random fertilization | random combination of genetically unique sperm and egg |
| Nondisjunction | failure of chromosomes or chromatids to separate correctly during meiosis |
| Karyotype | organized display of chromosomes arranged in homologous pairs |
| Trisomy | condition in which an individual has an extra chromosome |
| Monosomy | condition in which an individual is missing a chromosome |
| Down syndrome | genetic disorder caused by an extra chromosome 21 |
| Klinefelter syndrome | condition caused by an extra X chromosome in males |
| Turner syndrome | condition in which a female has only one X chromosome |
| Trisomy X | condition in which a female has three X chromosomes |
| Deletion | loss of a chromosome segment |
| Duplication | repetition of a chromosome segment |
| Inversion | reversal of a chromosome segment |
| Translocation | attachment of a chromosome segment to a nonhomologous chromosome |
| Asexual reproduction | reproduction involving one parent and genetically identical offspring |
| Sexual reproduction | reproduction involving two parents and genetically unique offspring |
| Mitosis | cell division that produces two genetically identical diploid cells |
| Interphase | stage when DNA is replicated before cell division |
| Metaphase I | stage of meiosis where homologous pairs line up independently at the equator |
| Prophase I | stage of meiosis when crossing over occurs |
| Anaphase I | stage of meiosis when homologous chromosomes separate |
| Anaphase II | stage of meiosis when sister chromatids separate |
| Genetically identical | having the exact same DNA |
| Genetically unique | having different DNA combinations |
| Sexual reproduction advantage | increases genetic variation and adaptability in changing environments |
| Asexual reproduction advantage | allows rapid reproduction without needing a mate |
| Why does meiosis reduce chromosome number from diploid to haploid? Why does meiosis reduce chromosome number from diploid to haploid? | so fertilization can restore the diploid chromosome number instead of doubling it every generation |
| A human body cell has 46 chromosomes. How many chromosomes would a sperm cell contain? | 23 chromosomes |
| If nondisjunction occurs during meiosis, what can happen to the offspring? | the zygote may have too many or too few chromosomes, causing genetic disorders |
| During which stage does crossing over occur, and why is it important? | Prophase I; it increases genetic variation by exchanging DNA between homologous chromosomes |
| Why are offspring from sexual reproduction genetically different from their parents? | because of independent assortment, crossing over, and random fertilization |
| A scientist finds a cell with 23 chromosomes. Is the cell most likely haploid or diploid? | haploid because it contains one set of chromosomes |
| What is the major difference between Meiosis I and Meiosis II? | Meiosis I separates homologous chromosomes while Meiosis II separates sister chromatids |
| Why are males considered to have nonhomologous sex chromosomes? | because the X and Y chromosomes do not contain all the same genes |
| What would happen if meiosis did not occur before fertilization? | chromosome numbers would double every generation |
| Why does mitosis produce genetically identical cells? | because DNA is copied exactly and sister chromatids separate evenly |
| Why is independent assortment important for evolution? | it creates genetic diversity that allows populations to adapt |
| A zygote divides repeatedly to form an embryo. Which process is occurring? | mitosis |
| If a chromosome segment flips around backward, what type of mutation occurred? | inversion |
| Why are deletions usually more harmful than inversions? | deletions remove genes completely while inversions usually keep all genes present |
| How many daughter cells are produced by meiosis? | four haploid daughter cells |
| How many daughter cells are produced by mitosis? | two diploid daughter cells |
| A cell goes through division once and produces identical cells. Was it mitosis or meiosis? | mitosis |
| A cell goes through division twice and produces unique cells. Was it mitosis or meiosis? | meiosis |
| Why is meiosis necessary for sexual reproduction? | it creates haploid gametes needed for fertilization |
| What is the relationship between meiosis and fertilization? | meiosis creates haploid gametes and fertilization combines them to restore diploid chromosome number |
| If crossing over did not occur, how would genetic variation change? | genetic variation would decrease |
| What is one advantage of asexual reproduction? | organisms can reproduce quickly without finding a mate |
| What is one advantage of sexual reproduction? | offspring have more genetic diversity and better survival potential |
| Why are gametes genetically unique? | because of crossing over and independent assortment during meiosis |
| A karyotype shows three copies of chromosome 21. What disorder does the person most likely have? | Down syndrome |
| What process causes homologous chromosomes to separate? | Meiosis I |
| What process causes sister chromatids to separate during meiosis? | Meiosis II |
| Why is random fertilization important? | any sperm can fertilize any egg, creating many possible genetic combinations |
| How many genetically different gametes can humans produce through independent assortment alone? | 2^23 combinations |
| Why is mitosis important in multicellular organisms? | it allows growth, repair, and replacement of cells |
| A student says meiosis creates identical cells. Why is this incorrect? | meiosis creates genetically unique haploid cells due to crossing over and independent assortment |
| Which type of reproduction produces clones? | asexual reproduction |
| Why are homologous chromosomes important in meiosis? | they pair up and separate to ensure each gamete gets one chromosome from each pair |
Created by:
katdolan