Topic 3 Flashcards
(52 cards)
What are the two types of cells
Prokaryotic and Eukaryotic
What do Prokaryotic cells always have
- No nuclei or membrane bound organelles
- Diameter of 0.5-5ɲm
- DNA is free in the cytoplasm
- Always has a cell wall
- Ribosomes
- Circular DNA
- Cell surface membrane
- Mesosome –> infolding of the cell surface membrane, it is a site of respiration
- Cell wall
- Cytoplasm
What organisms have/are Prokaryotic cells
Bacteria and cyanobacteria
What can some Prokaryotic cells have but dont always have u get me
- Plasmid (small circle of DNA)
- Flagellum (hollow thread-like structure that rotates to move the cell)
- Capsule (slimy layer on surface for protection and prevention of dehydration)
- Pili (thin protein tubes that allow the cell to stick to surfaces)
What do Eukaryotic cells always have
- 20ɲm or more
- Nucleolus –> dense body that makes ribosomes
- Nucleus –> two membranes enclosed in an envelope, it contains chromosomes and nucleolus
- Rough endoplasmic reticulum –> hold ribosomes for transcription, made of flat membrane-bound sacks
- Smooth endoplasmic reticulum –> no ribosomes, makes lipids and steroids
- Golgi apparatus –> modifies proteins and packages them in vesicles for transport. Is made of flat membrane-bound sacks due to the fusion of vesicles from the ER
- Cell surface membrane –> phospholipid bilayer, proteins and molecules that surround the cell contents
- Ribosomes –> made of RNA and proteins, function is in translation for protein synthesis
- Lysosomes –> Spherical sacks with digestive enzymes, breaks down the cell when it dies, or unwanted structures
- Centrioles –> make spindle in nuclear division, made of hollow protein microtubules
- Mitochondrion –> has two membranes and is used for aerobic respiration
What is the rol of rER and golgi in order
- Once a protein has been made by the ribosome on the rER or in the cytoplasm, it enters the rER
- In the rER it folds to gain its 3D shape, enters a vesicle and travels to the Golgi
- The vesicle fuses with the Golgi and the protein enters the Golgi
- In the Golgi the protein gets modified
- After modification the protein is placed into another vesicle and transported to the cell surface membrane
- The vesicle fuses with the cell surface membrane and the protein is releases
What are mammalian gametes
- Gametes are sex cells
- Contain only half of the total genetic material (haploid, n=23)
- When two gametes fuse a diploid zygote (fertilised ovum cell) is formed (2n=46)
What is an ovum cell, and where does it store its food
- A large cell incapable of independent movement
- Travels along the oviducts via ciliated cells
- Its cytoplasm contains food reserves
What organisms have/are Eukaryotic cells
All living organisms, that are not bacteria or cyanobacteria
What can some Eukaryotic cells have but dont always have u get me
Don’t always have a cell wall
What is the structure of a sperm cell from head to tail
Head contains –> acrosome then haploid nucleus
middle contains –> mitochondiron
Flagellum
What is the structure of a ovum cell from outside to inside
Follicle cells
Zona pellucida (jelly like coating)
Cell surface membrane
Cytoplasm that contains –> Lipids, lysosomes and a haploid nucleus
How does fertilisation take place
- Sperm cell reaches ovum
- Follicle cells release chemicals and trigger the acrosome reaction
- Acrosome swells and fuses with sperm surface membrane
- The digestive enzymes in the acrosome are released
- The enzymes digest the follicle cells and the zona pellucida
- Sperm cell fuses with ovum membrane and the haploid nucleus is released
- Lysosomes release enzymes to harden the zona pellucida preventing any other sperms from entering the ovum membrane
- The two haploid nucleuses fuse
What is meiosis and to what numbers do chromosome replicate to
- Produces haploid cells in the ovaries, testes and anthers (in plants)
- Chromosomes replicate to produce 4n=92 chromosomes, then the cell divides four times to produce four haploid cells/gametes n=23
What is independent assortment
- Only one chromosome from a pair ends up in each gamete
* This is how genetically variation is possible
What is crossing over
- This is when chromatids that are next to each other break and re-join causing them to mix
- Chiasma –> site where the cross over took place
Where does crossing over take place
Chiasma
What is linkage and how does it work
- Genes are inherited individually if the gene is on a different chromosome or if it is far away from another gene on the same chromosome
- If two genes are at the same lotus they will be most likely be passed on to the gamete together (linkage)
- If genes are close together or at the same lotus, crossing over is unlikely
What is sex linkage and give an example
- Genes that are located on a sex chromosome that will be passed on with a determined sex
- E.g 8%chance of red-green colour blindness in men, only 0.5% in women, this is a sex linked condition as it comes on the X chromosome
What stage of the cell cycle synthesises the cells contents
Interphase
In what stage of the cell cycle do the chromosomes condense and spindels from
Prophase
In what stage of the cell cycle do the chromosomes more to the equator
Metaphase
In what stage of the cell cycle do the centrometes spilt and pull DNA to the pols
Late Anaphase
What is the last stage of the cell cycle
Telophase