studying cells Flashcards
Describe the structure and function of the nucleus. [6]
Structure
1. Nuclear envelope and pores OR Double membrane and pores;
2. Chromosomes/chromatin OR DNA with histones;
3. Nucleolus/nucleoli;
Function
4. (Holds/stores) genetic information/material for polypeptides (production) OR (Is) code for polypeptides;
5. DNA replication (occurs);
6. Production of mRNA/tRNA OR Transcription (occurs);
7. Production of rRNA/ribosomes;
Describe the structure and function of a mitochondrion
Structure
1- double membrane
2- inner membrane fully folded to form Cristae (increase SA )
3- Matrix(liquid part) containing mitochondrial DNA , ribosomes, protein and lipids
Function
1- site of ATP production by aerobic respiration
Describe the structure and function of Rough Endoplasmic Reticulum
Structure
1- highly folded membranes with 80s ribosomes embedded
2- the membrane is folded into flattened sacks called Cisternae
3- joined to the nucleus
Function
1- synthesis and transport of protein throughout the cell
Describe the structure and function of smooth endoplasmic reticulum
Structure
1- highly folded membranes flattened into sacks called Cisternae
Function
1- recombines glycerol and fatty acids to make triglycerides
2- packages triglycerides into vesicles and transports them to the golgi apparatus
Describe the structure and function of cytoplasmic ribosome
Structure
1- made up of subunits that are made of long strands of rRNA and ribosomal proteins
Function
1- site of protein synthesis from amino acids
Describe the structure and function of the golgi apparatus/body
Structure
1- flattened sacs made of membranes filled with fluid
2- golgi vesicles pinch off from the main membrane
Function
1- sorts, modifies and packages proteins and triglycerides into vesicles
2- golgi vesicles may be used to form lysosomes
*always involves Proteins
Describe the structure and function of lysosomes
membrane-bound oragnelle that stores and releases many hydrolytic enzymes
Describe the structure and function of cell surface membrane
Structure
1- made up of phosphplipids, specific transport proteins, and carbohydrates arranged into a Fluid Mosaic Model
Function
1- controls the passage of molecules in and out of the cell
Describe the structure and function of centrioles
Structure
- microtubules
Function
1- form a network of spindle fibres onto which chromosomes attach
2- pull chromosomes/chromatids apart during mitosis
*not found in plant cells
Describe the structures and functions of Chloroplasts( found in plants and algae)
1- Granum : stack of thylakoid membranes
2- Thylakoid membrane : contains chlorophyll for photosynthesis & ATP synthase enzyme to produce ATP
3- Stroma : fluid filled part, some photosynthetic reactions occur here
4- Starch grains : the energy storage molecule in plants
5- DNA and Ribosomes : contain their own DNA and 70s ribosomes for synthesis of enzymes needed for photosynthesis
Describe the structure and function of cellulose cell wall ( in plants and algae)
1- is very strong which limits the volume of water that can move into the cell and stops osmotic lysis ( bursting)
2- the wall is permeable to most molecules
3- has plasmodesmata which are gaps in cell walls that connect cell cytoplasm’s together to allow easy movement of water-soluble molecules
what are the cell walls in fungi made of
chitin
what are the differences between plant and animal cells
1- cellulose cell wall vs no cell wall
2- chloroplasts present( not in roots) vs no chloroplasts
3- large central vacuole vs no large central vacuole
4- carbohydrates stored as STARCH vs carbohydrates stored as GLYCOGEN
5- has no centrioles vs has centrioles
Explain why viruses are described as acellular and non-living. [2]
1- no cell(-surface) membrane OR Not made of cells;
2- (Non-living) have no metabolism/metabolic
reactions;
OR
Cannot (independently) move / respire / replicate / excrete
OR
(Have) no nutrition;
MRSGREN
describe the structure and function of a virus
- contain DNA/RNA which can single/double stranded
- surrounded by a protein coat called a capsid
- has attachment proteins which enable it to bind to host cells
- has enzymes that it uses to replicate its genetic information and insert it into the host cell DNA
Eukaryotic cells produce and release proteins. Outline the role of organelles in the production, transport and release of proteins from eukaryotic cells. [5]
1- DNA in nucleus is code (for protein);
2- Ribosomes/rough endoplasmic reticulum produce (protein);
3- Mitochondria produce ATP (for protein synthesis);
4- Golgi apparatus package/modify; OR Carbohydrate added/glycoprotein produced by Golgi apparatus;
5- Vesicles transport OR Rough endoplasmic reticulum transports;
6- (Vesicles) fuse with cell(-surface) membrane;
Compare & contrast Eukaryotic and Prokaryotic DNA [5]
Comparisons
1. Nucleotide structure is identical;
2. Nucleotides joined by phosphodiester bond;
OR Deoxyribose joined to phosphate (in sugar, phosphate backbone);
3. DNA in mitochondria / chloroplasts same / similar (structure) to DNA in prokaryotes;
Contrasts
4. Eukaryotic DNA is longer;
5. Eukaryotic DNA contain introns, prokaryotic DNA does not;
6. Eukaryotic DNA is linear, prokaryotic DNA is circular;
7. Eukaryotic DNA is associated with / bound to protein / histones, prokaryotic DNA is not;
State three differences between DNA in the nucleus of a plant cell and DNA in a prokaryotic cell.
Plant v prokaryote
1. (Associated with) histones/proteins v no histones/proteins;
2. Linear v circular;
3. No plasmids v plasmids;
4. Introns v no introns;
5. Long(er) v short(er);
The structure of a cholera bacterium is different from the structure of an epithelial cell from the small intestine. Describe how the structure of a cholera bacterium is different
1- Cholera bacterium is prokaryote;
2- Does not have a nucleus/nuclear envelope/ has DNA free in cytoplasm/has loop of DNA;
3 and 4 Any two from: [No membrane-bound organelles/no mitochondria / no golgi/no endoplasmic reticulum];
5- Small ribosomes only;
6- and 7 Any two from [Capsule/flagellum/plasmid / cell wall]
Name two structures found in all bacteria that are not found in plant cells.
1- Circular DNA (molecule in cytoplasm);
2- Murein cell wall OR Peptidoglycan cell wall OR Glycoprotein cell wall;
3- Small(er)/70S ribosomes (in cytoplasm);
Give one advantage of using a TEM rather than a SEM.
1- Higher resolution;
2- higher (maximum) magnification / higher detail (of image);
OR
3- Allows internal details / structures within (cells) to be seen / cross section to be taken;
The resolution of an image obtained using an electron microscope is higher than the resolution of an image obtained using an optical microscope. Explain why.
Shorter wavelength between electrons
OR
Longer wavelength in light (rays);
Give one advantage of using a SEM rather than a TEM.
Thin sections do not need to be prepared / shows surface of specimen / can have 3-D images;
Scientists use optical microscopes and transmission electron microscopes to investigate cell structure. Explain the advantages and limitations of using a TEM to investigate cell structure. [6]
Advantages:
1 Small objects can be seen;
2 TEM has high resolution;
3 Electron wavelength is shorter;
Limitations:
4 Cannot look at living cells;
5 Must be in a vacuum;
6 Must cut section / thin specimen;
7 Preparation may create artefact;
