HL Biology IB

What to include in a microscope diagram?

Title (underlined with a ruler), magnification, field of view, labels outside of the field of view (ruler)

How to use a microscope?

1) Plug in the microscope and turn on the light

2) Turn to the lowest objective lens

3) Place the slide on the stage and secure it with the clips, with the specimen under the light

4) Raise the stage as close as possible to the objective lens looking from the side

5) Use the fine focus controls to get the slide into focus

6) Switch to the next power and use the fine focus to adjust

Define magnification

the process of making something look bigger than it is

Define Resolution

ability to distinguish between two separate objects as distinct entities

How to use a graticule

Line up the graticule scale and the stage micrometer. Find the ratio of small lines (graticule) to big lines (micrometer) and convert to find out how much one small line is worth. The units in the stage micrometer are 1mm.

How many micrometers per one milimeter?

1000

How to calculate magnification.

Magnification=image size/actuall size

What is the cell theory?

Cells are the smallest unit of life, cells are derived from other cells, all living things are made from cells.

How to know your microscope magnification

10 (eyepiece lens) x objective lens

Is there a limit to magnification?

No because enlargement is always possible, but resolution will not improve.

Contrast light and electron microscopes

Light: inexpensive, simple specimen preparation, magnifies up to 2000. Electron: Expensive, complex specimen preparation, magnifies over x1,000,000.

What is a development in microscopy?

Fluorescent stains: highlight different parts of the cell,identify which makes it easier to identigy.

What is the plasma membrane and what is its function?

Semi-permeable outer boundary of cells, which controls what enters and leaves.

What is the cytoplasm and what is its function?

Fluid/jelly substance where chemical reactions occur.

What is DNA and what is its function?

Made up of nucleotides and contains the instructions for cell functions.

What is the difference between the size of prokaryotic and eukaryotic cells?

Prokaryotic: Smaller (1-10 micrometers), Eukaryotic: larger (5-100 micrometers)

What is the cell wall, and what is its function? (Prokaryotic)

The outer wall that provides shape and protection, is always present.

What is the DNA in prokaryotic cells like and where is it found?

DNA is naked, in one loop, and is located in nucleoid region

What is the difference between ribosomes in prokaryotic and eukaryotic cells?

Prokarkyotic: 70s, Eukaryotic: 80s

What are pili used for? (prokaryotic)

Attachment/sexual reproduction

What are flagella used for? (prokaryotic)

Movement

What is the difference between gram positive and gram negative? (prokaryotic)

Gram-positive: can retain crystal violet (dye). Gram-negative: can not retain crystal violet

What is the nucleus and what is its function?

Largest organelle which contains chromosomes (DNA), controls activity of the cell

What is the rough endoplasmic reticulum (rEr) and what is its function?

Network of cisternae covered in ribosomes (80s), which makes proteins and packs them into vesicles

What is the smooth endoplasmic reticulum (sEr) and what is its function?

Network of cisternae with no ribosomes. Makes lipids and sex hormones (also packs them into vesicles).

What are lysosomes and where are they found?

Vesicles containing enzymes that can digest organelles. Found in animal cells.

What is are mitochondria used for, and what is its structure?

Used for aerobic respiration. Contain their own DNA, 70s ribosomes, and have a double membrane.

Which organelles are found in all cells?

Plasma membranes, cytoplasm, DNA, ribosomes

What are the 8 processes of life?

homeostasis, metabolism, nutrition, excretion, growth, response to stimuli, movement, reproduction

What is the cytoskeleton and where is it found?

Microtubules and microfilaments which give the cell some structure. Found in animal cells.

What are centrioles and where are they found?

Centrioles are where the spindles grow out of for cell division. Found in animal cells.

What are cilia and flagella and where are they found? (eukaryotic)

Structures used for motion found in animal cells.

What are chloroplasts used for and where are they found?

Used for photosynthesis (contains own DNA and ribosomes) .Found in plant cells.

What are permanent vacuoles used for and where are they found?

Maintains pressure within a cell. Found in plant cells.

What is the cell wall of fungi made of?

Chitin

What is the benefit of cell compartmentalization?

It is more efficient, each organelle has a specific function.

What is centrifugation?

Spinning something at high speed and seperating it based on density

What is cell fractionation?

Separating different organelles by spinning a solution at different speeds in a centrifuge

What is the advantage of having the nucleus and cytoplasm speperated?

DNA is safeguarded, transcription and translation can be different processes, alowing for post transcriptional modifications 

What is an advantage of compartmentalisation in the cytoplasm of cells

allows for the correct pH and concentration for different enzymes (eg.Lysosomes)

Adaptations of the mitochondrion for production of ATP

Cristae increase the surface area, matrix contains enzymes, intermembrane space, protons are pumped into easy to reach correct concentration.

Adaptations of the chloroplast for photosynthesis

Thylakoid membranes provide huge SA/good for light absorption. The double membrane keeps it separate from cytoplasm, Thylakoid spaces within grana are small so easier to reach a concentration

Function of free ribosomes

Make proteins which are used within the cell

Function of membrane bound proteins

make proteins for outside of the cell

What are the sides of the golgi apparatus called

Cis side, closer to rEr. Trans side, closer to plasma membrane

Role of clathrin in receptor-mediated endocytosis

Substance attaches to a receptor and the plasma memebrane folds into a clathrin coated pit. It then benfs to form a vesicle which is coated in clathrin. The clathrin then breaks away to be used again.

what does differentiate mean 

to turn into specialized cells 

What are stem cells

unspecialized cells

Properties of ctem cells

Self-renewal, ability to divide endlessly. Potency, ability to differentiate

What is the hayflick limit

Differentiated cells can only divide 6 times

Where is the stem cell niche 

Bone marrow, hair foliciles, where stem cells exist 

How are our cells different if they have the same DNA

some genes are expressed and others are repressed

What are totipotent cells

Only cell able to make all cells, found in zygote very early on. Only cell which can make placental tissue.

Whate are pluripotent cells

Can make almost any type of cell, but cannot create a full organism (no placental tissue)

What are multipotent cells

Can make a limited number of cells, can be present throughout entire life (eg.bone marrow)

What are unipotent cells

Cells that can only mature into one type of cells 

Why must cells be small 

As cells get bigger, volume increases faster than surface area. This means that the surface area to volume ratio decreases (bad), and the rate at which materials enter/leave cell depend on SA

Why do cells need a large SA:VOL ratio?

Bigger cells could not transport nutrients in the cell quick enough and could not get rid of heat or waste quick enough so they would die. 

Adaptations of a RBC (SA:VOL)

Has no nucleus, creates a biconcave disk which increases SA. Oxygen can diffuse easier and can store more Hb.

Adaptations of type 1 and 2 pneumocytes in alveoli (SA:VOL)

Type1: squamous shape (flat) to minimize diffusion distance. Type2: Has microvili to increase SA, produces surfactant to decrease surface tension.

Adaptationf od cardiac muscle cells

Myogenic: initiates its own beat. Lots of mitochondria so it never tires (lots of energy(

Adaptations of sperm

Small so it can penetrate egg. Has a flagelum for movement. Has an acrosome which contains hydrolitic enzymes to penetrate egg membrane. 

Adaptations of egg cell (OVUM)

Cytoplasm stores nutrients. Has a zona pellucida and cortical granules to prevent polyspermy.