Biology Flashcards
What are the 3 points in the cell theory ?
- All organisms are composed of cells
- Cells are the basic unit of structure in organisms
- All cells come from pre-existing cells
What is the formula for magnification ?
magnification = (image size) / (actual size)
What is magnification ?
how many times bigger an image of something is compared to it’s real size
What is resolution ?
how clearly 2 objects close together can be seen as separate
What are the rules for biological drawings ?
- include magnification
- no crossed lines
- no arrows
- include title
How are electron microscopes different from optical microscopes ?
- Specimin must be dead (in a vacuum)
- Pictures in black and white
- Much higher maximum magnification
What are prokaryotic cells ?
- bacteria
What organelles are always present in a prokaryotic cell ?
- cell membrane
- cytoplasm
- cell wall
- nucleoid
- ribosome
Is bacteria DNA bacteria associated with proteins ?
no
What contains the DNA in a prokaryotic cell ?
Nucleoid or plasmids
What is the nucleoid ?
Loop of circular DNA free in the cytoplasm
What organelles are sometimes in a prokaryotic cell ?
- Plasmis
- Capsule
- Flagella
What do plasmids do ?
- carry genes that protect the cell from antibiotics
What is conjugation ?
Plasmids transferred from one cell to another via a pilus which forms between the 2 cells to transfer a copy of the plasmid.
What does a ribosome do ?
Protein synthesis (makes proteins)
- eg. enzymes
Which ribosomes are found in each cell ?
70s : Prokaryotic
80s : Eukaryotic
What is a capsule ?
Slime that surrounds the bacteria (only found in some)
Made from a thick polysaccharide
What does a capsule do ?
Prevent the prokaryotic cell from drying out
What is the structure of a Gram+ cell wall ?
Has peptidoglycan, inner membrane (prokaryotic)
What is the structure of a Gram- cell wall ?
Has peptidoglycan, inner + outer membrane (prokaryotic)
What does the cell wall do ?
Provide structure and stability
What can move across the cell membrane without the need of a protein ?
Uncharged molecules
What does the cell membrane consist of ?
Phospholipid bilayer, Proeteins, Cholesterol and glycoproteins
What does the channel protein do ?
Open and close to let molecules through
What does the carrier protein do ?
Lets specifically shamed molecules through
What are the passive movements ?
- Osmosis
- Diffusion (simple and facilitated)
all require no energy and move down conc. grad.
What are the active movements ?
- Active Transport
- Bulk transport (exocytosis, endocytosis)
all use ATP
What happens in the cytoplasm ?
Chemical reactions
What is the structure of the Nucleus ?
Nucleolus surrounded by nuclear membrane with nuclear pores
What is the function of the Nucleus ?
Contains DNA and RNA
What is mitochondria ?
Site of respiration
What are a pair of antagonistic muscles ?
One muscle relaxes (antagonist)
while another contracts (agonist)
What happens when myoblast (stem cell) join together ?
form muscle cells
What is a sarcomere ?
1 contractile unit
What is the A band ?
point of overlap between myosin and actin
What is the I band ?
either side of Z line overlap of titin and actin
What is the H band ?
Point of no overlap of myosin
What is the Z line ?
titin, wiggly and at the normal to the rest of the components
What is the M line ?
myosin, straight and at the normal to the rest of the components
What is the process of muscle contraction ?
1 - Calcium ions are in the zone of overlap between actin and myosin
2 - Calcium binds to troponin (weakens bond between actin and troponin-tropomyosin complex) -> Exposes active sites of actin
3 - Energized Myosin heads bind to actin active site -> Forms cross bridge
4 - Energy stored released as Myosin pivots (power stroke) -> energy released in the form of ADP + P
5 - Another ATP binds to Myosin head, link between Myosin head and active site broken -> Active site exposed
6 - Energy released from bond between ADP and P pivots Myosin head back to original position
What changes and stays the same during muscle contraction ?
The A band and H band shorten and pull together, producing tension
The M line stays the same
How does muscle relaxation occur ?
- An active process
Calcium falls and detatches rom tryponin
Active sites re covered by trypomyosin
How are muscles adapted for slow twitches ?
Energy via aerobic respiration
Lots of; mitochondria, capillaries, myoglobin (stores O₂)
Less of; glycogen, phosphocreatine, sarcoplasmic reticulum (stores calcium)
How are muscles adapted for fast twitches ?
Energy via anaerobic repiration
large diameter
Lots of; glycogen, phosphocreatine, sarcoplasmic reticulum (stores calcium)
Less of; mitochondria, cappilaries, myoglobin (stores O₂)
How is a sperm specialised ?
haploid Nucleus (half chromosomes)
lots of mitochondria for energy
flagella to aid in swimming
acrosome contains enzymes (digests outer egg)
How is an egg specialised ?
haploid nucleus (half chromosomes)
vesciles contain a substance to stop more than 1 sperm fertilising
cytoplasm full of energy
zona pellucida stop more than 1 sperm fertilising the egg
corona radiata supply proteins
How are white blood cells specialised ?
large nucleus
often have protrusions
found in blood and tissues to move to infections easily
How are red blood cells specialised ?
Biconcave shape to increase surface area : volume ratio (more diffusion of O₂ and CO₂)
No organelles so more room for haemoglobin -> carries O₂
What are columnar epithelium cells (respiratory system)
Cells that line the trachea and bronchi
How are columnar epithelium cells specialised ?
Lots of mitochondria
Cilia to move mucus away from the lungs
Goblet cells produce mucus to trap unwanted particles
How is Chronic Obstructine Pulminary Disease (COPD) caused ?
Cigarette Smoke slows cilia of columnar epithelial cells
Stop wafting away mucus and mucus builds up
Clogged airways -> coughing, which can rupture alveoli cells
Can also create an environment for pathogens to grow
