Topic 2 Cells, Viruses And Reproduction (X 2.2) Flashcards
(92 cards)
1
Q
What are the two categories of cells?
A
Prokaryotic cells
Eukaryotic cells
2
Q
8Common features of prokaryote cells
A
- Cell wall
- Capsule
- Cell membrane
- Mesosome
- Nucleoid
- Plasmids.
- Ribosomes
- Flagella and pili
3
Q
What are cell walls of bacteria made of?
A
Peptidoglycan
4
Q
What is the function of cell walls?
A
Prevents cell bursting and give bacteria its shape
5
Q
What are capsules made up of?
A
Various molecules
Eg starch or glycolipids
6
Q
Where are capsule found?
A
Only on some bacteria
7
Q
What are the functions of capsule?
A
Protects bacterium from drying out in certain conditions
Protects being discovered in the immune system
Can enhance the ability of bacteria to cause disease
8
Q
What is the function of cell membranes?
A
Control substances entering and exiting the cell
9
Q
What are mesosomes?
A
They are artefacts
10
Q
What is a nucleoid?
A
DNA in prokaryotic cells in the form of one long sing strand aka nucleoid
11
Q
Where is the nucleoid found in prokaryotic cells?
A
Free in the cytoplasm, not in a membrane
12
Q
What are plasmids?
A
Small circular loops of DNA
13
Q
What do plasmids do?
A
Circular DNA carried by bacteria
Can be transferred between bacteria, eg confer resistance to antibiotics
14
Q
What do ribosomes do?
A
Protein synthesis
15
Q
Compare ribosomes in prokaryotic and eukaryotic cells
A
Ribosomes in prokaryotic cells are smaller (70s)
Made up of 30S + 50S
16
Q
What does flagella do?
A
Movement for bacteria
17
Q
What are flagella and pili made up of?
A
Protein fibres called flagellum which are spun around like a motor
18
Q
What are pilus used for?
A
To help bacteria reproduce and communicate and attach to surfaces
19
Q
How can contents of cell be separated to determine size and mass?
A
Use a centrifuge
(Spinning at high speed, centripetal force separates cells of diff mass)
20
Q
What is the cell theory?
A
That everything is made up of cells
21
Q
How are organisms organised?
A
Cells Into tissues into organs into organ systems
22
Q
Define ultra structure
A
The details of inside of cell
23
Q
Define organelle
A
Each structure within a cell
24
Q
What is the structure of a nucleus?
A
Surrounded by a double membrane called nuclear envelope
Contains chromatins and nuclear pores
25
Function of nucleolus
Produces ribosomes and RNA
26
What are ribosomes made up of?
Ribosomal RNA and protein
27
What is the function of ribosomes?
Used during protein synthesis and assemble polypeptide
28
Describe the structure of Rough endoplasmic reticulum
Made from flattened sacs of membranes called cisternae
Has ribosomes dotted along the surface
29
What is the function of rough endoplasmic reticulum?
Folds and processes proteins made on the ribosomes
30
What is the smooth endoplasmic reticulum made up of?
Just cisternae
31
What is the function of smooth endoplasmic reticulum?
Manufacture lipids, phospholipid and steroids (hormones)
32
What is the structure of mitochondria?
Capsule shape filled with MATRIX
Has its own circular DNA in the matrix
33
What is the function of mitochondria?
Provide large SA for aerobic cellular respiration for ATP production
34
How permeable are cell walls?
Freely permeable
35
What membrane are chloroplasts?
Double membrane
36
What do chloroplasts contain?
Thylakoids
Granum (stack of thylakoids )
Chlorophyll
Stroma
37
What DNA is found in chloroplasts?
Circular dna
38
What is a vacuole in prokaryotes filled with?
Cell sap
39
What are the functions of vacuoles in prokaryotes?
Storage
Maintain cell shape
40
What is a tonoplast?
Membrane that surrounds the vacuole
41
What’s the function of tonoplasts?
Control osmotic potential of cells
42
How are centrioles found?
In A pair near the nucleus at right angles
Bundle of 9 microtubule triplets
Only in animal cells
43
What is the function of centrioles?
Used when cell divides,
Hold organelles together
44
What is cytoskeleton?
Fibrous network that fills the cytoplasm
45
What is cytoskeleton made up of?
Microtubules and microfilaments
46
What is the function of cytoskeleton?
Present in cytoplasm
Holds organelles together
Allow movement of organelles
Gives cells structure
47
How are lysosomes found?
In cytoplasm
Dark spherical organelles
48
Where are lysosomes produced?
In RER
49
What do lysosomes do?
Catalyse reactions eg breaking down old organelles (digestive enzyme)
Exocytosis (by fusing with cell membrane and release out of cell)
50
What is Golgi apparatus made up of?
Stacks of cisternae
And
Vesicles
51
What do Golgi apparatus look like?
Coral like
52
Describe the role of Golgi apparatus in secreting enzymes. (3 marks)
- vesicles containing protein/enzyme from rER **packaged** and **fuse** with Golgi
- proteins **modified**
- proteins leave in **vesicles**
- by **exocytosis** / vesicles fuse with cell membrane
53
What are stages in mitosis?
PMAT
prophase- dna condenses to chromosomes, nuclear envelope break down
Metaphase-centrioles form spindle fibres, align in equator
Anaphase- spindle fibres contract, centromeres divide to each pole, sister chromatids become individual chromosomes
- telophase- decondense of chromosomes, spindle fibres break down, nuclear envelope reform
54
What are stages of meiosis I and II?
P1- crossing over, nuclear envelope break down, centrioles move to opposite poles
M1- independent assortment of homologous pairs
A1- separate homo. Pairs pulled to poles, ATP used
T1- X
P2-2nd cell division
M2- random assortment of
A2- centromeres divide, random separation
T2- nuclear envelope reform
Cytokineses - 4 haploid cells formed
55
Compare mitosis and meiosis
Somatic cells vs gamete cells
1 vs 2 cell divisions
46 vs 23 chromosomes
2 identical diploid vs 4 different haploid cells
Growth rep are and reproduce, vs only sexual reproduction
56
What’s translocation in chromosomes?
When 2 non homologous parts of genes transferred not another, forming unbalanced length of chromosome
57
What is non disjunction?
When chromosomes didn’t seperate correctly at anaphase - one will have too many and one too few chromosomes
58
What are the oogenesis products called? And their number of chromosomes?
Primordial germ cell > mitosis> Oogonia (2n) > primary oocyte (2n) > secondary oocyte (n) + first polar body (at puberty)> ovum (n) + second polar body
59
What are the spermatogenesis products called? And their number of chromosomes?
Primordial germ cell (2n) > spermatogonia (2n) > primary spermatocyte (2n) > secondary spermatocyte (n) > spermatids > spermatozoa (tails)
60
What are the two nuclei that lands on sigma and digests its way down the style to the ovule?
Pollen tube nucleus
Generative nucleus
61
What are the stages and products of megametogenesis?
Megastore mother cells divide by *meiosis*, 4 haploid MEGASPORES produced, 1 grows (3 degenerates) and mitosis 3 times
Forms 7 cells (1 has 2 haploid polar nuclei)
62
What stain is used to identify stages of mitosis?
Toludine blue
63
Devise a method for student to investigate effect of waterlogged soil on mitosis in root cells (4 marks)
- same type of plant
- same length of root tip
- find mitosis index
- leave for the same period of time
64
Why must appropriate stain be used to see stages of mitosis? (2 marks)
Dye attaches to cells in order for chromosomes to be visible
65
Why is a juvenile aphid genetically identical to its parent?
Asexual reproduction via mitosis
DNA replication takes place,
Dividing sister chromatids equally
66
What chromosome mutation is Down’s syndrome?
Non disjunction
67
What is the role of enzyme ligase in DNA replication? (3 marks)
Join Okazaki fragments together
Via phosphodiester bonds
Between phosphate group and sugar
68
Which type of cell division produces female gametes in female bees?given fertilised eggs develop into diploid females, unfertilised eggs develop into haploid males.
Meiosis since they need to be fertilised
So forms haploid gametes
69
What holds 2 chromatids together?
CentroMEREs
70
Explain the significance of meiosis in living organisms (3 marks)
Allows genetic variation
So natural selection can take place for advantageous alleles
Better.chance of survival under evolving selection pressures
71
What are 2 advantages of mitosis?
Rapid reproduction
Doesn’t need another mate/plant
72
Describe the process of crossing over during meiosis (3 marks)
- 2 homologous chromosomes line up
- chiasmata forms, exchanging genetic info
- break in DNA
73
Why do cells carry out mitosis? 2 marks
Growth, repair and replace of cells
Produce genetically identical cells
74
How does translocation occur?
When a part of a chromosome breaks off and joins to a non homologous chromosome
75
What does the term allele mean?
Different form of a gene
76
What stains are used to identify gram positive or negative cell walls?
1. Crystal violet (attached to G+ only, becomes violet)
2. Rinse w water, add iodine solution
3. Red safranin (G- becomes pink)
77
Gram negative is more resistant bcs…
it has an outer phospholipid layer protecting the cell wall unlike the gram positive. The antibiotic is blocked from the cell wall by this phospholipid bilayer making it much more difficult to treat.
78
Describe the role of the Golgi apparatus in producing secreted enzymes. (3 marks)
- vesicles containing enzyme protein from rER fuse with Golgi
- proteins modified
- proteins leave Golgi in vesicles
- vesicles fuse with cell membrane by exocytosis
79
Why do eukaryotic cells need mitochondria but prokaryotic cells don’t? (2 marks)
- mitochondria compacts enzymes and substrates tgt in one place
- so enzyme reactions are faster
- bacteria can use their cell membranes to respire
80
Describe the effects of ethanol on plant cell membranes. (2 marks)
- damages phospholipid
- so cell membrane becomes more permeable
81
Explain the structure of the membrane controls the transport of polar molecules. (4 marks)
Head is hydrophilic - on the outside
Tail is hydrophobic on the inside
Polar / charged substances can’t pass through hydrophobic tails
Passes through carrier proteins instead
82
Describe how insulin is modified, packaged and secreted by a cell. (4 marks)
- rER insulin is **folded**
- insulin **packaged** into vesicles
- vesicles **fuse** with Golgi
- insulin structure modified by Golgi
- vesicles fuse with cell membrane and **exocytosis** to secret
83
What is the type of division that undifferentiated plant cells meristems undergo?
mitosis
84
Give 2 differences between the structures of a prokaryotic and eukaryotic cell. (2 marks)
Pro / Eu
No nucleus / yes
Smaller ribosomes, 70S / larger, 80S
Cell wall contains Peptidoglycan / does not
85
What do glycoproteins do on viruses?
Act as receptors
To bind to CD4 receptors
On T helper cells
86
Describe the structure of an enzyme.
- globular protein
- has active site
- has many small R groups on the outside of the enzymes
87
How to identify types of bacteria?
Take sample
- grow on selective media
- grow in antibiotics
- gram staining
- DNA profiling
88
What are the gram staining colours for gram positive and negative bacteria?
Gram **P**ositive - **P**urple
Negative - pink/red
89
Describe the events that take place in metaphase of mitosis. (2 marks)
- chromosomes line up in the **equator** of the cell
- spindle fibres attach to the chromosome/centromere
90
Explain why another type of drug, rather than antibiotics, has to be used to treat Zia virus infections. (2 marks)
- viruses do not have Peptidoglycan cell wall
- antiviral drugs used to inhibit replication
91
Describe what happens to the Zika RNA once it is in the cell (given it is not a retrovirus). (2 marks)
- translation takes place to make viral proteins
- more RNA produced
92
Give the meaning of the term tissue. (1 mark)
Cells that perform a similar function
