Biology- Unit 2 Flashcards
Describe the structure of the nucleus
Double membrane
Nuclear pores
Chromatin
Nucleolus
Describe the structure and function of the rough ER
Contains ribosomes
Folds and processes proteins made on the ribosomes
Describe the structure and function of the smooth ER
Like the rough ER with no ribosomes
Produces and processes lipids
Describe the structure and function of the Golgi
A series of flattened curved sacs with vesicles surrounding it
Processes and packages proteins and produces lysosomes
Describe the structure and function of the mitochondria
Double membrane
Inner membrane folded into cristae
Matrix
Where aerobic respiration takes place
Describe the structure and function of the centrioles
Hollow cylinders containing microtubules
Involved in cell division
Describe the structure and function of the ribosomes
80s in Eukaryote
70s in Bacteria
Describe the structure and function of lysosomes
Vesicles
Digestive enzymes
What does gram positive mean?
Cell wall comprised of thick layer of peptidoglycan
Violet/ purple under microscope
What does gram negative mean?
Cell wall is thinner
Outer lipopolysaccharide membrane
Red under microscope
What is a lysogenic virus?
Insert DNA into host cells DNA in the form of provirus
Provirus can stay dormant if virus produces repressor proteins
What is a lytic virus?
Insert DNA/RNA into cytoplasm of host
Viral genome is replicated independently
Lysis of host cell
Describe the order of mitosis
Interphase, prophase, metaphase, anaphase, telophase
Describe interphase
DNA replicates
Cell prepares to divide
Chromosomes and some organelles are replicated
Chromosomes condense to form chromatin
Describe prophase
Spindle fibres appear
Chromosomes condense
Spindles attach to chromosomes
Describe metaphase
Chromosomes align on the equator
Describe anaphase
Centromeres divide
Sister chromatids move to opposite poles
Describe telophase
Nuclear membrane reforms
Spindle fibres disappear
Describe cytokinesis
Cytoplasm divides
Parent cell becomes 2 daughter cells
IDENTICAL
When does crossing over occur and what does it entail?
Occurs between prophase 1 and metaphase 1 of meiosis
Exchange of sections of DNA between homologous chromosomes
What is independent assortment?
Various combinations of maternal and paternal chromosome arrangement
What is translocation?
Can be unbalanced or balanced
Involves genes breaking off one chromosome and attaching onto the other
What is an example of polysomy?
Down’s syndrome
What is an example of monosomy?
Turner’s syndrome
Describe spermatogenesis
1) Primordial germ cells divide several times to form spermatogonia
2) Spermatogonia grow without further division to form primary spermatocytes
3) P. spermatocytes undergo meiosis to form secondary spermatocytes
4) S. spermatocytes undergo meiosis to form spermatids
5) Spermatids differentiate and grow into spermatozoa
Describe oogenesis
1) Primordial germ cells divide by mitosis to form oogonia
2) Only 1 oogonium continues to grow to form a P. oocyte
3) First mitotis division forms one secondary oocyte and one polar body
4) Second mitotic division forms one haploid ootid and one polar body
5) Second mitotic division of polar body- die when the ootid develops
Describe mammalian fertilisation
Ovum-
Contains zona pellucida (protective coating)
Cortical granules cause zona pellucida to harden after sperm has fused
Follicle cells form protective coating around egg
Spermatozoa-
Acrosome contains enzymes that ‘digest’ zona pellucida
Cortical reaction occurs preventing polyspermy
Describe gametogenesis in plants
Pollen formation-
1) Diploid microspore in anther undergo meiosis- form 4 haploid microspores
2) haploid microspores undergo mitosis into pollen grains which consist of 2 nuclei
Ovum formation-
1) Diploid megaspore undergo mitosis, forms an ootid and 3 polar bodies
2) The ootid undergoes three mitotic divisions to form an embryo sac
