Module 2 Flashcards
Virus alive or not?
Viruses are not defined as
living organisms because they do not have the standard components of a cell – acellular, and cannot perform MRS GREN without a host
Eukaryotic vs Prokaryotic Cells?
− Eukaryotic = animal/plant cell, has membrane bound organelles (nucleus, endoplasmic reticulum, golgi body, lysosome, mitochondra)
− Prokaryotic = bacteria, has no membrane bound organelles
What are the 2 forms of Reproduction?
Sexual & Asexual
− Sexual Reproduction in Animals & Some Plants
− Asexual Reproduction in Microorganisms & Some Plants
− Sexual Reproduction uses 2 parents (each provides a gamete which fuse to form a zygote, zygote develops into organism)
− Asexual Reproduction uses 1 parent to produce genetically identical offspring
How does a Zygote develop into an Organism?
Zygote is a stem cell
− stem cell = undifferentiated/unspecialised cell, can form any type of cell
− zygote divides by mitosis to make many stem cells
− each stem cell differentiates into specialised cell
− each specialised cell divides by mitosis to make many copies and form a tissue
− different tissues join to form an organ
− different organs join to form an organ system
− this is surrounded by the Body
Define a tissue, organ and organ system?
tissue = a group of specialised cells
organ = made of different tissues
organ system = different organs working together
What is an Animal Cell made of?
Organelles (nucleus, endoplasmic reticulum, golgi body, lysosomes, mitochondria, ribosomes) – all have membrane except the ribosomes
− Cytoplasm (site of chemical reaction)
− Cell Membrane (holds cell contents together, controls what enters/leaves cell, cell signalling)
Structure of Nucleus?
contains DNA (made of genes, genes code for making proteins)
− DNA wrapped around histones to form Chromatin
− nucleus has a double membrane, called Nuclear Envelope, which contains pores
− at centre of nucleus is Nucleolus – produces mRNA (copy of a gene)
− rest of nucleus made of Nucleoplasm (contains the DNA/chromatin)
Endoplasmic Reticulum?
2 types = Rough and Smooth
− Rough Endoplasmic Reticulum has ribosomes on it, makes proteins
− Smooth Endoplasmic Reticulum has no ribosomes on it, makes lipids/carbohydrates
Golgi body?
modifies and packages proteins
− packages them into vesicles for transport
− digestive enzymes are placed into lysosomes (vesicles with membranes around them)
Mitochondria?
site of respiration, releases energy, produces ATP (energy carrier molecule)
− has a double membrane, inner membrane folded into Cristae (increases surface area for enzymes of respiration)
− middle portion called Matrix
Ribosomes?
attached to RER
− site of protein synthesis
What is a Plant Cell made of?
Organelles (nucleus, endoplasmic reticulum, golgi body, lysosomes, mitochondria, chloroplast, vacuole, ribosomes) – all have membrane except the ribosomes
− Cytoplasm (site of chemical reaction)
− Cell Membrane (holds cell contents together, controls what enters/leaves cell, cell signalling)
− Cell Wall (made of cellulose, prevents cell from bursting or shrinking)
Structure of chloroplast?
organelle for photosynthesis
− has double membrane
− contains discs called thylakoids
− thylakoids contain chlorophyll
− stack of thylakoids called granum
− thylakoids surrounded by a fluid called stroma
Vacuole?
Surrounded by a membrane called a tonoplast, contains Cell Sap (water, sugar, minerals)
What is Bacteria made of?
No nucleus – loose DNA in the form of a single loop and plasmid
− No membrane bound organelles: smaller ribosomes, mesosomes – infolding of cell membrane for respiration
− Cytoplasm
− Cell Membrane & Cell Wall (made of peptidoglycan/murein)
− some have a Capsule (reduce water loss, protect from phagocytosis) and Flagella (movement)
What is Virus made of?
DNA or RNA (if RNA, also has a enzyme called reverse transcriptase to turn RNA into DNA)
− Protein Coat called Capsid and Lipid Coat
− Attachment proteins on outside
− (infects host cells by attaching using their attachment protein, send in their DNA which uses the cell to make the viruses components and uses the cell membrane to make the viruses lipid coat, hence, producing copies of the virus and destroying the host cell)
What is a Chromosome?
DNA in coiled form
− formed during interphase of cell division (mitosis/meiosis) in Animals/Plants
− made of 2 identical/sister chromatids joined by a centromere
− carries 2 copies of the same DNA molecule
What is a homologous pair of chromosomes?
a pair of chromosomes: 1 maternal (from mother)/1 paternal (from father)
carries same genes but different alleles – there are 23 pairs in humans
What is Cell Division?
formation of new cells in multicellular organisms (animals & plants)
− 2 methods = mitosis & meiosis
− mitosis = produces genetically identical cells for growth & repair of tissues
− meiosis = produces genetically different haploid cells as gametes for sexual reproduction
What does Mitosis (cell cycle) produce?
2 genetically identical cells, diploid (have full set of chromosomes/DNA)
Benefit of Mitosis?
growth and repair of tissues
Stages of Mitosis?
Interphase/Mitosis/Cytokinesis
Mitosis?
Prophase: DNA coils to form chromosomes, nucleus breaksdown, spindle fibres form
Metaphase: chromosomes line up in middle of cell and attach to spindle fibre via centromere
Anaphase: spindle fibres pull, centromere splits, sister chromatids move to opposite sides
Telophase: chromatids uncoil, nucleus reforms (left with 2 genetically identical nuclei)
What happens to DNA mass in mitosis?
What happens to Chromosome number in mitosis?
halves
stays the same (diploid)
What is Cancer?
formation of a tumour due to uncontrolled cell division (uncontrolled mitosis)
How does uncontrolled cell division occur?
due to mutation of DNA/cells forming cancer cells
− mutation can occur randomly or due to mutagens (chemicals/radiation)
− cancer cells are rapidly dividing cells (like hair cells, skin cells, red blood cells), they spend less time in interphase and more time in the other stages (mitosis)
Treatment for Cancer?
Surgery = aim is to remove tumour
Chemotherapy = - using drugs that inhibit mitosis in rapidly dividing cancer cells
- problem, also affect normal healthy cells (hair cell, skin cells, rbcs) causing side effects (hair loss, dry skin, tiredness)
- treatment given as regular doses to allow time for normal healthy cells to recover in number
Radiotherapy = radiation used to destroy cancer cells
What does Meiosis produce?
4 genetically different cells, haploid (half the amount of chromosome/DNA)
Benefits of Meiosis?
produces gametes which will be used in sexual reproduction in animals & plants
(2 gametes fuse to form a zygote, zygote develops into organisms)
Stages of Meiosis?
Interphase
Meiosis I
Meiosis II
Cytokinesis
Metaphase I:
homologous pair of chromosomes line up in middle of cell and attach to spindle fibre via centromere by random assortment
What is HIV/AIDs?
− HIV is spread by fluid to fluid contact (unprotected sexual intercourse, sharing needles, mother to child via placenta or breast feeding)
− HIV damages and destroys T Helper Cells, therefore person no longer produces Immune Response and has no defence to against pathogens/infections = AIDs
− With AIDs, individual at risk from all sorts of pathogens/infections called Opportunistic Infections
What is antigenic variability?
the pathogen mutates, the antigen changes shape, so the memory cells no longer complementary – do not recognise the pathogen, therefore the pathogen can reharm
Problems with Vaccination Programmes?
− vaccine does not work (dead form ineffective, pathogen hides from immune system)
− vaccine not safe (no weak/inactive form, causes major side effects)
− many strains of pathogen
− cannot achieve herd immunity (logistic of vaccinating large proportion)
− antigenic variability
What is herd immunity?
when a large proportion of the population is vaccinated, therefore most people will be immune, only a few will not be a immune, increases chance of non-immune person coming into contact with immune person, so the pathogen has no where to go, so it dies out
Successful Vaccination Programme?
−
produce suitable vaccine (effective – make memory cells, does not cause disease, no major side effects, low cost, easily produced/transported/stored/administered)
− herd immunity
How does passive immunity occur?
naturally = from mother to baby (placenta or breast milk),
artificially = by injection
How does activity immunity occur?
naturally = by primary infection, artificially = by vaccination