3.2.1 Cell Structure Flashcards
What are the inner folds of mitochondria called?
Cristae
What is the function of the Golgi Apparatus?
To process & package new proteins & lipids; makes lysosomes.
What is the function of a lysosome?
Contain enzymes- lysozymes used to digest broken/invaded cells.
What is a ribosome made of?
Proteins, RNA
What is the function of a ribosome?
Protein synthesis
Describe the difference between smooth & rough endoplasmic reticulum.
Smooth= no ribosomes
What is the function of the smooth ER?
Synthesises & processes lipids
What makes up the cell wall of plants & algae?
Cellulose
What is a tonoplast?
The membrane of a vacuole
Why would an epithelial cell in the small intestine need lots of mitochondria?
Respiration, to give energy needed for absorption of nutrients by active transport
What is a tissue?
A group of similar cells performing a similiar function e.g. epithelial cells form epithelial tissue
What is an organ?
A group of similar tissues working together e.g muscular, epithelial & glandular tissues form the stomach.
Describe the function of the nucleolus.
Makes ribosomes
Give 2 differences between plant & fungal cells.
Fungi= no chloroplasts & chitin cell wall not cellulose
List 3 differences between eukaryotic & prokaryotic cells.
Prokaryotic = no membrane bound organelles, no nucleus, smaller ribosomes, murein cell wall
What is a plasmid?
A loop of DNA NOT part of main chromosomal DNA e.g. genes for antibiotic resistance. Not in all bacterial cells.
Why might a bacterial cell have a slime capsule?
To give protection against the cells of the immune system, to stop too much water leaving the cell and to protect against antibiotics
Why do prokaryotes undergo Binary Fission?
Bacteria replicate using binary fission
What replicates in Binary fission?
Chromosomal DNA replicates once- plasmids may replicate many times
What is the role of the attachment proteins of a virus?
To allow viruses to invade host cells, by using complemetary binding to receptors on host cells.
Briefly describe the steps of viral replication.
- Viruses attach to host cells using attachment proteins 2. Genetic material is released into host cell 3. Host cell machinery replicates viral DNA/RNA/proteins 4. Viruses assemble & replicate 5. Viruses leave host cell
Describe the term resolution.
Level of detail seen in an image- how close together 2 objects are to be seen as separate.
Describe the term magnification.
The number of times larger an image of an object is compared with the actual size.
Describe 2 differences between a light microscope & SEM.
SEM- higher resolution (3-10nm rather than 200nm), higher magnification (200,000 rather than 2000), uses electrons rather than light, can see surface of cells- 3D image
Write down the formula for magnification.
magnification = size of image/ size of real object
1mm = ? μm
1mm = 1000 μm
50 μm = ? cm
0.005 cm
1mm = ? nm
1mm = 1,000,000m
Use standard form to write the number 0.00002 mm
2 x 10-5
List 3 organelles you cannot view with a light microscope.
ribosomes, ER, lysosomes
Describe when you would use a TEM.
To view a thin specimen, high resolution to see small objects.
Why is a stain used when preparing a slide?
Stains highlight objects in a cell- you can see certain organelles more clearly.
Why does a specimen need to be thin when preparing a slide?
Thin specimens allow light to pass through the object, so can be seen clearly.
Describe what an artefact is.
Artefacts are viewed underneath a microscope but should not be there e.g. air bubble, dust, fingerprint and usually arise from inaccurate preparation of a sample.
List the 3 steps involved in cell fractionation.
Homogenation, filtration, ultracentrifugation
What is the heaviest organelle?
nucleus
What are the lighest organelles?
ribosomes
Explain why an ice-cold, isotonic, buffered solution is used in cell fractionation.
Ice- cold: slow enzyme activity, Isotonic: prevent damage to organelles, Buffered: control pH
What type of microscope would you use to study lysosomes?
TEM
Which type of microscope would be used to study replication of E.coli bacteria?
Light
Which type of microscope would be used to study the 3D structure of a red blood cell?
SEM
Describe what happens to a cell in interphase.
DNA unravels & replicates, organelles replicate & ATP increases.
What is the ultimate outcome of mitosis?
2 genetically identical daughter cells
Describe 2 uses of mitosis by organisms
For growth & repair of human cells (e.g. skin) embryonic development, asexual reproduction of plants.
List the stages of mitosis in order.
Prophase, Metaphase, Anaphase, Telophase
What is a centromere?
The centre point of a chromosome- holds 2 sister chromatids together.
What is a centriole?
Bundles of protein, which produce spindle fibres and move to poles of the cell in prophase.
Describe what occurs in Prophase.
Nuclear envelope breaks down, centrioles move to either end, chromosomes condense.
List 2 events that happen in Metaphase.
Chromosomes lines up on spindle equator, spindle fibres attach to centromeres.
Describe what cells would look like when undergoing anaphase.
No nuclear envelope, v-shaped chromatids being pulled apart to opposite ends of the cell.
List 2 events that happen in Telophase.
Chromatids uncoil & nuclear envelope reforms.
What is cytokinesis?
Final stage of mitosis where the 2 joined cells separate into 2 daughter cells.
If 10 cells out of a total of 100 are in metaphase of mitosis & one complete cycle takes 15 hours, how long do the cells spend in metaphase? Give answer in minutes.
15 x 60 = 900 , 10/100 x 900 = 90 mins
Briefly, what causes cancer?
When the cell cycle is out of control (gene mutation)
Vincristine is a cancer drug which prevents spindle fibres from formed. Briefly describe how this will help to treat cancer.
No spindle = no anaphase so mitosis cannot occur, cells can’t divide & cancer can’t develop further.
How can the overall magnification of a light microscope be calculated?
Objective lens x occular lens (usually x10)
What is the mitotic index?
The proportion of cells in a sample undergoing mitosis.
Write down the formula for mitotic index.
Mitotic index = number of cells with visible chromosomes / total number of observed cells
What is an eyepiece graticule?
A transparent ruler, attached to the eyepiece used to measure actual size of cells.
Would you expect the mitotic index of root tip cells to be higher or lower than cells from a mature leaf?
Higher- root tip divides to extend.
Description and function of the cell wall?
rigid structure, mainly made of cellulose, that surrounds and supports plant cells.
Description and function of the chloroplast
small flattened structure. has a double membrane and membranes inside called thylakoid membranes. thylakoid membranes are stacked up in some parts to form grana. grana are linked together by lamellae (thin pieces of thylakoid membrane). Site of photosynthesis
What is a capsid?
Protein coat around the core of a virus
What is the envelope on a virus?
outer layer of lipid formed when the virus ‘buds’ off and breaks away from a host cell
Describe the basic structure of a virus
A strand of nucleic acid (DNA or RNA) enclosed within a protein coat
Describe the Golgi apparatus
A group of fluid filled membrane bound flattened sacs. formed by the fusion of vesicles from the ER
Describe the mitochondria
Double membrane- inner one is folded to form a structure called cristae. Inside is the matrix which contains enzymes involved in respiration
What is the function of the mitochondria?
site of aerobic respiration, where ATP is produced. found in large numbers in cells that are very active and require a lot of energy.
What is the function of the centriole?
Involved with the separation of chromosomes during cell division
What is the flagellum?
long hair like structure that rotates to make the prokaryotic cell move. not all prokaryotes have a flagellum and some have more than one
What is mitosis needed for ?
Growth, repairing damaged tissues and for asexual reproduction
What does the cell cycle consist of ?
Interphase which is a period of cell growth and DNA replication (G1, S and G2) then Mitosis
What is the purpose of the capsule in bacterial cells?
Made of secreted slime protects the bacterium from attack by cells of the immune system. also prevents dehydration and allows bacteria to form colonies
What is the bacterial cell wall made of?
made of murein glycoprotein
Name the 4 bases found in DNA, name the bonds that form between them
Adenine - Thymine and Guanine -cytosine. Hydrogen bonds
