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A Level Biology Paper 1 > Cells and Organelles > Flashcards

Cells and Organelles Flashcards

(44 cards)

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1
Q

Define Eukaryotic

A

True nucleus
DNA enclosed in a nuclear membrane
Membrane organelles

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2
Q

Examples of eukaryotes

A 
Plants
Animals
Fungi
Algae
Protozoan
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3
Q

Nucleus function

A

Contains DNA which stores genetic information to synthesise proteins
Controls cell activity

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4
Q

Structure of the nucleus

A

Nuclear envelope/double membrane: contains nuclear pores to allow for passage of molecules like mRNA into and out of the cell

Nucleolus: where ribosomal RNA (rRNA) and ribosomal subunits are synthesised in the nucleus (assembled elsewhere)

Chromatin: made of DNA that has been coiled around histones, and supercondenses in cell division to form structures called chromosomes

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5
Q

Mitochondrion function

A

Site of ATP synthesis via aerobic respiration

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6
Q

Structure of mitochondrion

A

Double membrane: inner is highly folded to form cristae which increase the surface area for attachment of ATP synthase

Matrix: a liquid within the inner membrane that contains proteins, lipids, mitochondrial DNA and ribosomes

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7
Q

RER function

A

Rough Endoplasmic Reticulum

Synthesises and transports proteins throughout the cell

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8
Q

RER structure

A

Made from highly folded membranes with 80s ribosomes embedded

Membrane folded into flatterned sacs called cisternae

Joined to the nucleus so easier for mRNA to get into nucleus to make proteins

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9
Q

SER function

A

Smooth Endoplasmic Reticulum

Recombines glycerol and fatty acids to make triglycerides

Packages triglycerides into vesicles and transports them ti the golgi apparatus

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10
Q

SER structure

A

Highly folded membranes with no ribosomes attached

Folded into flatterned sacs called cisternae

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11
Q

Ribosome function

A

Site of protein synthesis from amino acids

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12
Q

Ribosome structure

A

2 subunits containing rRNA and ribosomal proteins

The subunits are a combination of long strands of rRNA dotted with ribosomal proteins

Eukaryotes contain 80s (also 70s in mitochondria or chloroplasts)

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13
Q

Golgi apparatus function

A

Sorts, modifies and packages molecules like proteins and triglycerides into vesicles

Can be used to form lysosomes

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14
Q

Golgi apparatus structure

A

Composed of flattened sacs made of membranes

Sacs are fluid filles and pinch off into smaller sacs at the end (vesicles)

Usually only one in each cell

Well developed in secretory cells because large volumes of molecules must be processed sorted and packaged into vesicles for transport out of cell

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15
Q

Vesicles function

A

Transports molecules around the cell and out of the cell

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16
Q

Vesicles structure

A

Small fluid filled sacs found at the end of the golgi apparatus

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17
Q

Lysosome function

A

Contain the hydrolytic digestive enzymes lysozymes to hydrolyse damaged and worn out components of cells

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18
Q

Lysosome structure

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A

Single membrane

No clear internal structure

Contain a large number of hydrolytic enzymes called lysozymes that are kept in an acidic solution and separate from the rest of the cell to prevent organelle digestion

19
Q

Microvilli function

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A

Increase surface are of cells

20
Q

Microvilli structure

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A

Finger like projections of the cell membrane that increase the surface area for faster absorption of food

Found on epithelial cells in the small intestines

21
Q

Function of centrioles

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A

Involved in mitosis to form a network of spindle fibres across the cell onto which the chromosomes attach

Spine fibres pull the chromosomes apart

22
Q

Structure of centrioles

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A

Not found in plants

Cylindrical structures found in perpendicular pairs near the nuclear membrane in the cytoplasm

23
Q

Function of the plasmodesmata

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A

Allows for substance exchange between adjacent plant cells

24
Q

What are some key differences between plant and animal cells

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A

1) Plant has cellulose cell wall/Animal no cell wall
2) Plants have chloroplast present/Animal no chloroplast
3) Plants have large central vacuole/Animal no large central vacuole
4) Plants store carbohydrates as starch/Animals store carbohydrates as glycogen
5) Plants have no centrioles/Animals have centrioles
6) Plants have plasmodesmata/Animals have no plasmadesmata

25
Chloroplast Function
Absorb light energy and convert it into chemical energy (done by the chlorophyll and other pigments) Chemical energy used to make carbs from CO2 and H2O Which can then be used for respiration or to make other organic molecules to enable growth
26
What's the structure of chloroplast
Double membrane for protection Granum = Stack of thylakoid membranes Thylakoid membranes = Contain chlorophyll for photosynthesis Stroma = Fluid filled part, some of photosynthesis reactions occur here (+enzymes) Starch grains = Energy storage in plants DNA and Ribosomes = Have their own DNA and 70s ribosomes to make enzymes needed for photosynthesis
27
How are chloroplast proof of evolution
They have 70s ribosomes like prokaryotes
28
Define Prokaryotic
Before nucleus No nuclei or other membrane bound organelles DNA is circular and does not form chromosomes, floats freely in the cytoplasm and not associated with histones
29
Function of flagella
Provides motility | Can have 0,1,2 ....
30
Function of mesosomes
Provide a larger surface area for the attachment of respiratory enzymes
31
Function of pilli
Help bacteria/prokaryotic cells attach o surfaces | Connect between bacteria, allowing horizontal DNA (plasmid) transfer
32
Function of plasmids
Have extra genetic material and genes for antibiotic resistance Can be transferred between bacteria via pilli
33
Bacterium cell membrane
Murein (peptidoglycan)
34
What is the function of the slime capsule
Made of secreted polysaccharides Helps them cling to eachother and to surfaces Prevents the cell from dying out
35
Contrast prokaryotic and eukaryotic cells

Circlular DNA Linear DNA

Not associated with histones Associated with histones

No membrane bound organelles Membrane bound organelles

DNA free floating in cytoplasm DNA in nucleus

70s ribosomes 80s (70s in some organelles)

Capsule and plasmids Neither

Mesosomes for ATP syntase Mitochondria for ATP synthase

Murein cell wall No cell wall/Plants cellulose

36
What is a viruses class
No | Acellular
37
Structure of virus
- DNA or RNA that can be single or double stranded - That's surrounded by a protein coat called a capsid - Attarchement proteins allow it to bind to host cell - Enzyme it uses to replicate its genetic information and insert this into the host cells DNA
38
Explain plant cell walls
Cellulose in plant and algae Very strong because many weak H bonds between fibrils which limit volume of water that can move into cell (prevents osmotic lysis) Permeable to most molecules unlike cell membrane Cell qalls of adjacent plant are separated by thin layer called middle lamella which acts to stick walls together with pectin Plasmodesmata are gaps that allow easy movement of small water soluble molecules and connect cells to cytoplams
39
Why can't viruses self replicate
They have no organelles so unable to replicate independently They can't synthesise protein or DNA to make copies of themselves Need a host to do it for it
40
Advantage of inserting genes into eggs
Gene gets into all of orgabism | So gets into cell that it's meant to (relate to Q)
41
How to prepare mount for microscope
``` Add drop of water to glass slide Thin section and place ontop Stain (with iodine) Avoid trapping air bubbles Lower cover slip slowly with mounted needle ```
42
How does interphase and mitosis produce 2 genetically identical cells
DNA replication semiconservative involving complementary based pairing Two identical sister chromatids Each moves to opposite poles
43
Why should specimen be thin for light microscope
So more light can get through | So fewer cells can be viewed
44
Why does carbon dioxide uptake drop in dark
No light no photosynthesis so no need No diffusion gradient for it to enter the leaf No diffusion gradient for it to leave due to respiration

A Level Biology Paper 1 (16 decks)

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