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Bio Exam Unit 7
Asexual v. Sexual reproduction, mitosis, cancer, meiosis
| Question | Answer |
|---|---|
| How many organisms does asexual reproduction require? | 1 organism |
| What is the result of sexual reproduction? | Offspring that are exact genetic ‘clones’ (same DNA) of their parents |
| Does asexual reproduction result in genetic variation? | No |
| What is binary fission? | Division of bacteria/protists into two |
| Which organisms can perform binary fission? | Only unicellular organisms |
| What is divided in binary fission? | Equal division of nucleus and cytoplasm |
| What is parthenogenesis? | Females eggs develop into offspring without the need of a male to fertilize it |
| What is budding? | An offspring “buds” or grows right out of the body of the parent |
| What are two examples of organisms that do parthenogenesis? | Whiptail Lizards and Komodo Dragons |
| What are two examples of organisms that do budding? | Hydra and Yeast |
| What is fragmentation? | A parent breaks into multiple pieces, and each piece develops into a fully functioning, independent individual |
| What is an example of an organism that does fragmentation? | Starfish |
| What is vegetative propagation? | Flowering plants produce new plants from their roots, stems, or leaves |
| What are two examples of vegetative propagation? | Runners and cuttings |
| How many organisms does sexual reproduction require? | Involves 2 parent organisms |
| What happens in sexual reproduction? | Joining of gametes (egg and sperm) |
| What is the result of sexual reproduction? | Offspring is genetically different from both parents |
| Does sexual reproduction result in genetic diversiy? | Yes |
| What are four important aspects of asexual reproduction? | 1. Cells divide by Mitosis 2. Creates genetically identical offspring (clones) 3. Works best for a stable, unchanging environment 4. Helps a population colonize an area quickly |
| What are four important aspects of sexual reproduction? | 1. Cells divide by Meiosis 2. Mixing of genes from mom and dad creates genetic variation 3. Genetic Variation is good in a changing environment 4. Requires male and female gametes and is slower than asexual reproduction |
| What is mitosis? | the division of the nucleus |
| What are somatic cells? | Body cells - (non-reproductive cells, so everything except egg and sperm) Ex: skin, muscle, liver, blood, etc. |
| Why do cells need to do mitosis? | Growth, replace, repair, and reproduction |
| What important material needs to be copied before cell division? | Chromosome |
| What is chromatin? | Threadlike unwound pieces of DNA |
| What is chromosome? | Condensed (coiled up) chromatin - Tightly packed |
| What are two identical copies of DNA called? | Sister chromatids |
| What protein holds together a pair of sister chromatids? | Centromere |
| What organelle makes spindle fibers? | Centrioles |
| What do spindle fibers do? | Pull chromosomes apart during cell division |
| What are spindle fibers part of? | The cytoskeleton |
| What are the three main stages of the cell cycle? | Interphase, mitosis, and cytokinesis |
| What is the point of interphase? | The cell grows |
| What is the point of mitosis? | Nucleus divides |
| What is the point of cytokinesis? | Cell separates into 2 daughter cells |
| What is the longest stage of the cell cycle? | Interphase |
| What % of a cell's life is spent in interphase? | 98% |
| What are the three stages of interphase? | G1 phase (first gap phase), S phase (synthesis phase), and G2 phase (second gap phase) |
| What happens in G1 phase? | Cell grows in size and carries on normal functions (just being a cell) |
| What happens in S phase? | DNA Replication – chromosomes copied |
| What is the purpose of S phase? | So new cells can have an exact genetic copy |
| What happens in G2 phase? | Cell continues to grow and centrioles and other structures needed for division are made |
| At what point does a cell HAVE To carry out cell division? | G2 phase |
| What happens in mitosis? | Process by which somatic cells make lots of identical “daughter” cells |
| What happens after replication? | Mitosis |
| What are the four steps of mitosis? | Prophase, metaphase, anaphase, and telophase |
| What happens in prophase? | Chromatin condenses into chromosomes (become visible) |
| What are the 2 signs of prophase? | Nuclear membrane begins to disappear and spindle fibers appear from centrioles (spindle fibers attach to chromosomes at the centromere) |
| What happens in metaphase? | Chromosomes line up in the middle of the cell |
| What alliteration can help you remember where metaphase is in the cell cycle? | Metaphase Middle |
| What happens in anaphase? | Chromosomes are pulled apart to opposite ends of the cell, separating sister chromatids |
| What alliteration can help you remember where anaphase is in the cell cycle? | Anaphase Away |
| What rhyme can help you remember what happens in anaphase in the cell cycle? | When the phase begins with A, the sister chromatids get pulled away |
| What happens in telophase? | Spindle fibers break down, chromosomes unwind back into chromatin, and two new nuclear membranes form (opposite of metaphase) |
| What is cytokinesis? | Division of the cytoplasm |
| What is a cleavage furrow? | Cell membrane pinches in (only in animal cells) |
| What is a cell plate? | Add new cell wall to separate cells (only in plant cells) |
| What do you have at the end of Mitosis? | Get 2 exact genetic copies of original parent cell "clones" |
| What phrase can help you remember mitosis? | IPMAT |
| Where does mitosis occur? | Somatic (body) cells |
| What controls the start and stop of the cell cycle? | Enzymes and Cyclin Proteins |
| What is cancer? | Uncontrolled cell division – cell does not respond to normal ‘stop’ signals |
| What does uncontrolled cell growth result in? | Mass of cells (aka tumor) |
| Why is cancer fatal? | It deprives normal tissue of nutrients |
| What are the two types of tumors? | Benign and malignant |
| What is a benign tumor? | An abnormal mass of NORMAL cells |
| What is a malignant tumor? | Masses of cells that result from the reproduction of CANCER cells |
| What is metastasis? | The spread of cancer cells beyond its original site |
| When is cancer caused? | When cells with errors pass through checkpoints in cell cycle that would normally cause cell death and mutations in DNA alter the function or production of proteins regulating the cell cycle |
| What causes mutations in DNA, and thus, cancer? | Carcinogens |
| What are carcinogens? | Substances that mutate our DNA causing our cells to divide uncontrollably |
| What are the three carcinogens? | Radiation, Environment, and Viruses that damage genes |
| What are two examples of radiation? | UV rays and X-rays |
| What are three examples of environmental carcinogens? | cigarette smoke, toxins in air, and pollution |
| What is one example of a gene damaging virus? | HPV |
| How can cancer be removed? | Surgery, radiation, and chemotherapy |
| How many complete sets of chromosomes does each cell have? | 2 |
| How many chromosomes are in 1 human cell? | 46 chromosomes |
| How many pairs of chromosomes are in one human cell? | 23 pairs |
| Where do the sets of chromosomes come from? | 1 set from the mother and 1 set from the father |
| What are the corresponding chromosomes in each set called? | Homologous chromosomes |
| What are homologous chromosomes? | Pairs of chromosomes that are similar in size, shape, and contain the same genes (one comes from mom and the other from dad) |
| What does "n" refer to in terms of chromosomes? | The number of types of chromosomes (Ex: n=23 2n = 46 for human cells) |
| What is a diploid cell? | A cell with 2 of each type of chromosome (have 2 complete sets) |
| Are body cells diploid or haploid? | Diploid |
| What is a haploid cell? | a cell with only 1 of each type of chromosome (only 1 complete set) |
| What are the only haploid cells? | Sex cells (aka gametes) |
| How is a zygote made? | Two haploid gametes make one upon fertilization |
| What is a zygote? | A single cell that made by two gametes that will grow into a baby |
| Where does meiosis happen? | In ovaries and testis |
| What does meiosis do? | Produces gametes (egg and sperm) |
| What is the difference between meiosis and mitosis? | They are the same except in meiosis the process happens twice |
| Why does there have to be 2 divisions in meiosis? | To become haploid |
| What happens in meiosis I? | Homologous chromosomes separate and the reduction division (diploid → haploid) |
| What happens in prophase I? | Chromosomes become visible, nuclear membrane disappears, homologous pairs come together forming tetrad, and crossing over occurs |
| What is a tetrad? | 4 chromatids together |
| What is crossing over? | Exchange genes between homologous chromosomes (Shuffles genes to produce unique combinations) |
| What is genetic recombination? | Crossing over (recombine genes) |
| What is the source of genetic variation in gametes? | Genetic recombination |
| During Meiosis, what happens in metaphase I? | Tetrads line up in the middle |
| During Meiosis, what happens in anaphase I? | Pairs of homologous chromosomes separate but sister chromatids are still attached |
| During Meiosis, what happens in Telophase I and Cytokinesis? | Homologous chromosomes reach opposite sides and 2 nuclei form, Cytoplasm divides, and Daughter cells are haploid at this point! |
| In what two ways does meiosis create genetic variation? | Independent assortment and crossing over |
| What is independent assortment? | The position of homologous pairs at metaphase I is a matter of chance. (line up randomly) |
| What DOES'NT happen in meiosis II? | No interphase between Meiosis I and II |
| What happens in meiosis II? | Sister chromatids are separated |
| What happens in prophase II? | Chromosomes condense, nuclear membrane dissolves, and Spindle fiber forms (no crossing over) |
| What happens in metaphase II? | Sister chromatids line up at middle (Because of crossing over in meiosis I, the chromatids are unique) |
| What happens in anaphase II? | Spindle fibers contract and pull sister chromatids to opposite sides |
| What happens in Telophase II and Cytokinesis? | Nuclear membrane reforms, chromosomes uncoil into chromatin, After cytokinesis, get 4 haploid cells (these cells are gametes – sperm and egg) |
Created by:
suiter.mayhew
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