BIOLOGY TOPIC 1 CELL BIOLOGY
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BIOLOGY TOPIC 1 CELL BIOLOGY - Marcador
BIOLOGY TOPIC 1 CELL BIOLOGY - Detalles
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| What are the 3 principles of cell theory? | All living things are made of cells cells are the smallest unit of life cells only come from pre-existing cells |
| What are some exceptions to cell theory? (3) | Striated muscle fibres aseptate fungal hyphae giant algae |
| How is striated muscle fibres an exception to cell theory? | Individual cells fuse to form long multinucleated fibres = challenges the idea that cells always work as autonomous units |
| How is aseptate fungal hyphae an exception to cell theory? | Hyphae may be connected with a continuous cytoplasm (no cellular partitions = challenges the idea that living cells are made of separate cells |
| How is giant algae an exception to cell theory? | Certain species are very large = challenges the idea that organisms are always made of many microscopic cells |
| What are the 7 functions of life? | Metabolism = undertakes important chemical reactions Reproduction = produces offspring sexually/ asexually Sensitivity = responsive to internal / external stimuli Homeostasis= maintain a stable internal environment Excretion= remove toxic waste products Nutrition = exchanges materials with the environment Growth: changes shape / size / position |
| What is the order of the cell scale? | M (metre) mm (milli) u (dash on left) um (micro) = cell, organelle, bacteria (b=>s) nm (nano) = virus , membrane, molecule (b=>s) pm (pico) = to become smaller you need to *1000 |
| What are the functions of life in paramecium (heterotroph)? | Metabolism: food particles enclosed in vacuoles with enzymes for digestion Reproduction: divides asexually (mitosis) Sensitivity: cilia responds and detects stimuli Homeostasis: gases enter and exit with diffusion Excretion: waste products removed by anal pore and liquids pumped out with contractive vacuoles Nutrition: engulf food with feeding grove Growth: cilia helps move the cell |
| What are the functions of life for chlorella (Autotroph)? | Metabolism = chlorophyll makes organic molecules with photosynthesis Reproduction = asexual (mitosis) Sensitivity = sensitivity towards light (phototaxis) Homeostasis: keeps equilibrium inside Excretion + Nutrition = exchange gases by diffusion Nutrition: photosynthesis Growth: Non-motile |
| Differences between light and electron microscope (2) | Light: uses visible light to views living specimen in colourand has lower resolution and magnification Electron: dead specimens in black and white, higher resolution and magnification |
| How to calculate magnification? | M = Image size / actual size |
| How to calculate Actual size? | A = Image size / magnification |
| What does the surface area and volume of a cell affect? | Volume = metabolism rate (larger cells need more energy to function) Surface area = material exchange rate (large membrane surface = more material movement) |
| What should be included when drawing microscopic structures? | Name of organism magnification scale structures that can be SEEN should be labelled |
| How do cells carry out metabolism? | Cells produce chemical energy by metabolism by exhanging materials with the environment |
| What does growth of cell lead to and what helps prevent this problem from happening? (3) | As a cell grows V + faster than SA = decreased SA:VOL ratio if metabolic rate > material exchange rate = cell will die SO = growing cells divide and remain small to keep a high SA:Vol ratio |
| How to calculate total SA? | H *W * Sides * no of boxes |
| How to calculate total volume? | H * W * L * No of boxes |
| How can cells / tissues increase SA: Vol ratio? (3) | Cells that are specialized for gas or material transfer will increase SA to optimize material transfer eg: intestinal tissue in the digestive tract can have villi to increase SA of the inner lining eg: Alveloi in lungs has microvilli (membranous extensions) to increase SA |
| How do emergent properties form? (3) | When groups of individual cells work together = these organisms can do new functions (Emergent properties) because of the collective action of many cells combining to create synergistic effects eg: cell (muscle) = Tissue (cardiac) = Organ (heart) = System (cardiovascular) |
| What is differentiation? | When newly formed cells become more specialized and distinct from one another as they mature during development |
| How do cells differentiate? (2) | All cells of an organism have an identical genome (entire set of genetic instructions) activation of different instructions (Genes) within a cell by chemical signals = differentiation |
| What are the two different types of gene packaging? (3) | Euchromatin: active genes that are packaged in an expanded and assecible form heterochromatin: inactive packaged in condensed and inaccessible form |
| What are stem cells? (3) | Unspecialized cells that can: self renew (continuously divide and replicate) potency (capacity to differentiate into specialized cell types) |
| What are the 2 main types of stem cells? (2) | Embryonic stem cells (totipotent / pluripotent) can form any cell type adult stem cells (multipotent / unipotent) limited capacity for differentiation |
| What are all 4 types of stem cells? | Totipotent: form any cell type and placental tissue (zygote) pluripotent: form any cell type (embryonic) multipotent: differentiate into a number of closely related cell types (Adult) unipotent: can't differentiate, but can self renew (muscle stem cells_ |
| What are the uses of stem cells? | Needed for embryonic development (undifferentiated = all the other cells come from it replaces damaged / diseased cells that can't self renew with healthy functioning cells |
| What is the process of stem cell therapy? | Stem cells are extracted from embryos, umbilical cord blood or certain adult tissues (bone marrow) biochemical solutions trigger differentiation new cells are implanted into host tissue immune system is suppressed to stop rejection new cells are monitored to see that they aren't cancerous |
| What are 2 specific diseases that SCT is used with? | Stargardts disease: it is an inherited form of juvenile macular degeneration = blindness Treated by replacing dead cells in retina with functioning ones Parkinsons disease: degenerative disorder caused by the death of dopamine secreting cells (CNS) treated by replacing dead cells in midbrain with functioning ones show tremors and rigidity and slow movement as dopamine is an NT used for smooth movements |
| What are the ethical considerations with the use of stem cells? | Embryos are specially created with the highest potency however it is the highest risk of developing into a tumor and involves destruction of an embryo Umbilical cord blood is easy to extract but it has a lower potency and the cells must be stored from birth at a cost Adult tissues are cells that can be taken at any life stage but it has the lowest potency and could be difficult and painful to extract |
| What are 2 methods of artificial stem cell production? | Somatic cell nuclear transfer (SCNT) = creating embryonic clones by fusing a diploid nucleus with a enucleated egg cell more embryos than needed are created = raises ethical concerns of excess embryos Nuclear reprogramming: cause a change in gene expression profile of a celll = different cell type (transdifferentiation) Uses oncogenic retroviruses and transgenes = cancer |
| What are prokaryotes? (3) | Lack compartmentalisation (no memmbrane bound organelles unicellular Can exist as different shapes such as rods or spirals |
| What are the features of a prokaryote (and function) (6) | Nucleoid: region in cytoplasm where DNA is located, (DNA strand is circular = genosphere) Plasmids: autonomous circular DNA molecules that can be transferred bw bacteria (horizontal gene transfre) 70S ribosomes: RNA + protein for translation Cell wall: outer covering made of peptidoglycan to maintain shape and prevent bursting Slime capsule: thick polysacch layer for protection against dessication (drying out) and phagocytosis Flagella: long progections w/ motor protein for movement (flagellum) Pili: hair like extensions to stick to surfaces / mediates bacterial conjugation |
| What are plasmids able to do? (4) | Plasmids are autonomous molecules of circular DNA they can be transferred bw bacteria by BACTERIAL CONJUGATION mediated with a sex pilus = exchange of genetic characteristics |
| Draw a bacteria with labels (9) | Cell wall peptidoglycan cell membrane cytoplasm plasmid nucleoid genosphere ribosomes 70s pili slime capsule glycocalyx flagellum |
| How do pros asexually reproduce? | By binary fission DNA is copied as a response to a replication signal 2 DNA loops attach to the membrane membrane elongates and pinches off by cytokinesis = 2 distinct cells |
| In what ways to pros and euks differ? (4) | DNA pros: naked + circular DNA euks: bound to protein + linear DNA Organelles pros: no membrane bound organelle + 70S ribosomes euks: membrane bound organelles + 80S ribosomes Reproduction pros: binary fission + haploid euks: mitosis and meiosis + diploid Average size pros: small (1-5 micrometers) euks: large (10-100 micrometers) |
| What are eukaryotes? (4) | Complex cells with a nucleus compartmentalised cellular structure membrane bound organelles believed to have come from pros by endosymbiosis |
| What are organelles? | Specialised sub structures in cells to do a specific function |
| What are the 4 types of eukaryotes? | Protista: unicellular / multicellular without specialised tissue fungi: chitin cell wall and are heterotrophs plantae: cellulose cell wall and are autotrophs Animalia: no cell wall and are heterotrophs |
| Draw an animal cell (9) | Mitochondria Smooth + rough ER cytoplasm cell membrane ribosomes 80s golgi apparatus nucleus nucleolus Lysosome |
| Draw a plant cell (10) | Golgi apparatus smooth and rough ER nucleus ribosomes 80S cell wall cellulose chloroplast vacuole mitochondria cell membrane cytoplasm |
| Which organelles are present in both pro and euk? | Ribosomes cell membrane cytoplasm |
| Which organelles are only present in plant cells? | Chloroplasts vacuole cell wall (cellulose) |
| What is the structure and function of ribosomes? (3) | 2 subunits made of RNA and protein (80s in euk and 70s in pro) site of polypeptide synthesis (translation) |
| What is the structure and function of the cell membrane? (2) | Phospholipid bilayer embedded with proteins semi-permeable + selective barrier around the cell |
| What is the structure and function of the nucleus? (3) | A double membrane structure with pores has an inner region (nucleolus) stores genetic material (DNA) as chromatin and nucleolus is site of ribosome assembly |
| What is the structure and function of the endoplasmic reticulum? (3) | A membrnae network that can be smooth / rough (w ribsomes) transports materials between organelles smooth ER = lipids rough ER = proteins |
| What is the structure and function of the golgi apparatus? | A group of vesicles and folded membranes near cell membrane sorts and exports secretory products |
| What is the structure and function of a mitochondrion | Double membrane structure = inner membrane highly folded site for aerobic resp = ATP production |
| What is the structure and function of peroxisome? | Membranous sac with catabolic enzymes catalyses breakdown of toxic substances (H2O2) |
| What is the structure and function of centrosome? | Microtubule organizing centre with paired centrioles in animal cells radiating microtubules = spindle fibres which help with cell division (mitosis and meiosis) |
| What is the structure and function of chloroplasts? | Double membrane structure with internal stacks of discs site for photosynthesis = make organic mols that are stored in plastids |
| What is the structure and function of a vacuole? | Fluid filled internal avity surrounded by tonoplast maintains hydrostatic pressure |
| What is the structure and function of cell walls? | Outer covering made of cellulose provides support + mechanical strength and stops excess water uptake |
| What is the structure and function of lysosomes? | Membranous sacs filled with hydrolytic enzymes breaks down macromolecules |
| What are the two types of cells? | Pros: have no nucleus ( archaea + bacteria) euks have a nucleus (protista, fungi, plantae and animalia) |
| What are the two types of prokaryotes? | Archaea = found in extreme environments (high temps = extremophiles) Eubacteria = bacteria in pathogenic forms (E. Coli) |
| What is the cell cycle? (8) | Events which lead to the cell dividing into 2 daughter cells Interphase - happens before division has 3 stages: G1 =cell growth and metabolism S = DNA replication G2 = Cell growth and preparation M Phase - cells divide to create 2 daughter cells 2 stages: Mitosis = nuclear division Cytokinesis = cytoplasmic division |
| What is mitosis? | Process of nuclear division whereby copied DNA molecules are arranged into 2 nuclei |
| What happens during interphase? (4) DOCT | DNA replication (DNA copied during the S phase) Organelle duplication (organelle copied for twin daughter cells) Cell growth (cytoplasmic volume increases before division) Transcription / translation (key proteins and enzymes are synthesised) |
| How is DNA usually packed in the nucleus? (2) | Chromatin = loosely packed in an accessible form in the nucleus can be transcripted and translated |
| How is DNA packaged before cell division? (4) | Chromosome = chromatin supercoils to become tightly wound and condensed easily grouped but inaccessible for transcription condenses in prophase decondenses in telophase |
| How is DNA packed during the S phase in interphase? what happens after? (2) | During S phase, the chromosome has 2 identical DNA strands (sister chromatids) which is held in the middle with centromere During mitosis when they separate they are each made of a single DNA strand = daughter chromosomes |
| What are the 4 stages of mitosis? PMAT | Prophase Metaphase Anaphase Telophase division of cell in two (cytokinesis) is after the final stage |
| What happens during interphase? (3) | DNA is uncondensed (Chromatin) and is in the nucleus organelles are duplicated cell is enlarged for division |
| What happens during prophase? (PRO = before) (3) spindles | DNA supercoils and chromosomes condense (made of identical sister chromatids) paired centrosomes moved to the opposite poles of the cell and form microtubule spindle fibres nuclear membrane breaks down |
| What happens during metaphase? (MIDDLE) (3) | Chromosomes align in the middle microtubule spindle fibres connect to the centromeres of each chromosome spindle fibres contract bec of microtubule depolymerisation |
| What happens during anaphase? (AWAY) (2) | Sister chromatids separate and move to opposite poles of the cell because of spindle fiber contraction |
| What happens during Telophase? (3) | Spindle fibres dissolve chromosomes decondense nuclear membrane reforms around the 2 chromosome sets |
| What happens during cytokinesis? | LAST STAGE: cytoplasmic division whereby the cell splits into 2 |
| Describe cytokinesis in animal cells? (3) | Microtubule filaments form a ring (cleavage furrow) which contracts in the center of the cell cells become PINCHED off = 2 cells are formed cells separation = centripetal (starts outside and moves to the centre) |
| Describe cytokinesis in plant cells? | Vesicles form at the centre of the cell and fuse to form an early c plate cells separation = centrifugal |
| What is the mitotic index? what is it used for? (3) | A measure of the proportion of dividing cells mitotic index increases during cell division is used to predict the response to chemotherapy from cancer cells |
| Mitotic index formula | Cells in mitosis / total cell number |
| How would you identify mitotic cells? | They lack a clearly defined nucleus and the condensed chromosomes are visible P = chromosomes are condensed in a nucleus M = chromosomes are aligned in the middle A = 2 clusters of chromosomes at poles of the cell T = 2 nuclear regions in a single cell |
| Functions of mitotic division (TOAD) | Tissue repair = damaged / aged cells are replaced with new cells Organismal growth = multicellular organisms make new cells Asexual reproduction = natural cloning (vegetative propagation) Development of embryos = zygotes divide and differentiate to form embryos |
| What is the mitotic index? | Measure of the proliferation status of a cell population (proportion of dividing cells) |
| What are the cell cycle checkpoints to regulate the cell cycle? (3) | G1 = checks if the cell is ready for DNA replication (S phase) G2 = checks if the cell is ready for mitosis M = checks that the cell is ready for cytokinesis |
| What are cyclins? What do they activate? what do they do? (4) | 1) family of regulatory proteins that control cell cycle progression 2) activate cyclin dependent kinases (CDK) by forming a complex with it 3) The complex phosphorylates a target protein = a specific cell cycle event 4) After the event the cyclin is degraded and CDK inactivated |
| Why do cyclin concentrations need to be tightly regulated? (3) | To make sure the cell cycle happens in a proper sequence diff cyclins bind and activate diff CDKs cyclin levels peak when their target protein is needed for function and remains at lower levels at other times |
| How does cell death occur? | Once cells reach their proliferative capacity = cell division stops |
| What is the aging phase for cells called? | Senescence (aging) phase = cell death |
| What are the two different types of cell deaths? | Cell death can be uncontrolled (necrosis) or programmed (apoptosis) |
| What is the difference between apoptosis and necrosis (2) | Apoptosis - controlled destruction of a cell in response to molecular signals uses mitochondrial proteins cell contents are packaged into vesicles and recycled Necrosis - premature death due to injury or nutritional deprivation cells becomes destabilised Cell contents are released into tissues = inflammation |
| Why do cyclin concentration need to be tightly regulated? (3) | To ensure that the cell cycle happens in a proper sequence different cyclins bind and activate different cyclin dependent kinases cyclin levels peak when the target protein is needed and remains at lower levels at other times |
| What is cancer? | Uncontrolled cell division and can occur in any tissue or organ |
| What is a tumor? 2 types | The abnormal cell growths formed from cancer (uncontrolled cell division) Primary = stay in the original tissue (BENIGN GROWTHS) Secondary = invade neighboring tissues (MALIGNANT GROWTHS) |
| What is metastasis? | Spread of cancerous tissue from one place to another |
| How are secondary tumors defined? | Defined and treated according to the original cell type eg: breast cancer spreads to liver = secondary breast cancer of the liver |
| What is a mutagen? example? (4) | An agent that causes a change in the genetic material of an organism either acts on the DNA or replicative machinery can be physical, chemical or biological carcinogens = formation of cancer |
| Examples of physical mutagens? (Radiation) (3) | X-rays (ionising) = medical UV (sunlight) radioactive decay |
| Examples of chemical mutagens? (3) | Carcinogen (cigarettes) processed foods cleaning products |
| What are examples of biological mutagens? (3) | Viruses (HPV) bacteria (helicobacter) mobile genetic elements (transposons) |
| Examples of mutagens? (7) | Radiation = physical UV ( sunlight ) X Rays (medical) Chemicals = chemical Carcinogen (cigarettes) processed foods cleaning products Infectious agents = biological Viruses (HPV) Bacteria (helicobacter) |
| What is an oncogene? | A gene that could cause cancer |
| Which mutations to 2 genes causes cancer? | Proto-oncogenes = code for proteins that increase cell growth When mutated: cancer causing oncogene tumor suppressor genes = code for proteins that repress cell cycle progression and promotes cell death = if mutated or undergoes increased expression it becomes a cancer causing oncogene |
| What is the correlation between smoking and lung cancer? | There is a positive correlation 90% Cancer rates are higher in countries with higher rates of smoking increases risk of other cancers such as mouth, stomach, liver |