DP Biology Flashcards

Cells

Extremely small and only visible under microscope

Smallest alive part of an organism

Single-Cell or Multi-Cells to make up organisms

Unicellular Organism

An organism made up of a single cell

Multicellular Organism

An organism made up of multiple cells (ex. humans)

Features of a Cell

Consists of a nucleas surrounded by Cytoplasm contained within the cell membrane.

Nucleus

Structure that controls and directs activities of a cell. Done in the form of the Deoxyribonucleic acid (DNA) nucleic acid.

Cytoplasm

Contains tiny structures called organelles (in both animal and plant cells)

Plant Cells

Tough and slightly elastic cell wall made up of cellulose (mostly). Have large vacuoles that are permanent. Contain Chloroplasts and store starch. Manufactures sugars via photosynthesis that are used to create biochemicals for metabolism. They respire aerobically with energy transferred to maintain cell functions.

Animal Cells

Has no cell walls and temporary small vacuoles. contains centrosomes and stores glycogen. Respires aerobically with energy transferring to maintain cell function. Digestion produces the biochemicals needed for metabolism using the energy from respiration. Loss of water is excreted from across the cell surface. Reproduces via nuclear division followed up by transverse constriction of the cytoplasm. The cells rotate as they swim rapidly through the water, and within it, food vacuoles within can be seen being carried around by cytoplasm. Typically detects food particles and moves towards it and small cells with grow to full size before it divides.

Vacuoles

Fluid filled space in the cytoplasm surrounded by a single membrane

Centrosome

Organelle involved in nucleur division in animal cells and lies close to nucleus

Magnification Formula

Size of image / Size of Speciment

Plasma membrane

Materials required for growth and maintenance of cell growth which can be found on the outermost layer of the cytoplasm. It’s a barrier of sorts and it must be crossed by all metabolites to move between the cystosol and the enviornment of the cell.

Rate of material entering and leaving a cell

Dependent on surface area of cell

Rate of material use and waste production from cell activity

Dependent on amount of cytoplasm in cell

Suface area:Volume Ratio

As the cell grows bigger, the ratio drops with less of the cells interior having access to the external environment. This leads to slower and more difficulty during cell exchange of materials. This also means that once a certain size is acheived, cell growth stops occurring and this may be the point in which cells decide to split

Metabolism of a cell

Not linked to surface area but the amount of cytoplasm in a cell expressed as cell mass

Tissue(s)

Group of similar specialised cells to perform a specific function

Organs

Collection of different tissues which perform a specialized function

Gene

1. Specific region of a chromosome which is capable of determining the development of a specific characteristic of an organism

2. Specific length of the DNA double helix which codes for protein

Acellular organisation

Multinucleate organs and organisms not divided into different cells

Cell Cycle

2 types

1. Young Cell to Cell division to Cell Growth and they continue to grow and divide repeatedly rather than specialise (eg. Bone Marrow Stem Cells)

2. Young Cell to Cell Division to Cell Growth to Cell Specialization to Mature Cell unlikely/unable to divide again until they die by programmed cell death (PCD)

Stem Cells

Cell that has capacity for repeated cell division while maintaining an undifferentiated state (self-renewal) and subsequent capacity to differentiate inro mature cell types (potency). They are the essentials for life in multi-cellular organisms as they divide and form cells that form a range of mature cells that aid in different functions.

Embryonic Stem Cells

Undifferentiated cells capable of continual cell division and of developing into all the cell types of an adult organism. These make up the bulk of an embryo as it commences development.

Adult Stem Cells

Undifferentiated cells capable of cell divisions, these give rise to a limited range of cells within a tissue, for example blood stem cells give rise to red and white blood cells and platelets only

Manafacturing Stem Cells for Medical purposes

If isolated in viable cell cultures with large quantities, it’s no doubt a valuable medical prospect into repairing or replaced damaged organs. This would require though for the cells to continue to divide in the environment, be able to differentiate into the specific cells desired, be viable in the patients body and intergrate into that function and operate correctly without triggering any harmful reactions within the body (primarily the tissues).

Eukaryotic Cells

Means good nucleus cells referring to the obvious and large nucleus and the surrounding cytoplasm contains many different membranous organelles. Contains cell compartmentalisation and made up of a well-organised system of microtubles which shape and support the cytoplasm.

Prokaryotic Cells

Meaning before the nucleus, these are bacteria that contain no nucleus and their cytoplasm don’t contain the same organelles as Eukaryotic cells.

Cytosol

Aqueous solution/fluid that surrounds organelles in living cells. Contained within plasma membrane

Metabolism

Chemicals in the Cytosol are formed and used in chemical reactions of life.

Eukaryotic Nucleus

Typically the largest cell in a eukaryotic cell, 10-20 micrometres in size typically.

Microtubles

Unbranched hollow cylinders, straight and 25 nanometres wide. Involved in movement of other cell components within the cytoplasm.

Tubulin

The globular protein that the system of microtubles are made up of. Built up and broken down in the cell as required for different places and tasks.

Mitochondria

Mostly rod-shaped or cylindrical shaped organelles with occasional variantions when observed in electron micrographs. Typically 0.5-1.5 micrometre wide and 3.0-10.0 micrometres tall. Found in all cells in large quantities that are more prevalent in metabolically very active cells cytoplasm. They have double membranes with the outer membrane being a smooth boundary whilst the inner membrane is folded to form cristae and the interior is full of matrix. This is the site of the aerobic stages of respiration

Matrix

Within the mitochondria, the interior is filled with an aqueous solution of metabolites and enzymes.

Mesophyll

May be packed with 50 or more chloroplasts

Chloroplasts

Manufacture food through photosynthesis. 4-10 micrometres long and 2-3 micrometres wide. Most occur in the mesophyll cells of leaves of green plants. Contains a double membrane with an outer layer of continuous boundary and the inner layer of thylakoids.

Thylakoids/Lameallae

Inner layer of chloroplast membrane consisting of a system of branching membranes

Hydrophobic

Not much chemical attraction to water molecules.

Hydrogen Bonds

The bonds between a hydrogen molecule in one H2O and an oxygen molecule in another H2O

Electronegativity in Water

Oxygen is more electronegative which leads to the electrons in the covalent bond between oxygen and hydrogen staying more on the side of the oxygen. This leads to the oxygen becoming partially negative and the hydrogens becoming partially positive. This gives water a polar covalent bond.

Cohesion

The attraction of water molecules towards each other through hydrogen bonds. Pulls water together making it ‘stick together’ and may counteract gravity (for example, the xylem or in a domed droplet)

Surface Tension and water

Due to cohesion, water has a strong surface layer since the hydrogen bonds that can’t connect to particles above connect to other H2O molecules creating a stronger layer on the surface of a water droplet

Tardigades

Microscopic animals renowned for the ability to survive nearly drying

Desication

Process of removing/extracting water content thoroughly resulting in extreme dryness

Capillary Action

When water is pulled through narrow tubes and space as a result of cohesion and adhesion. Occurs when adhesion is greater than cohesion. Sands and soils use it to make all layers have water (hence why the top layer of soil isn’t dry). It’s also used in plants to move water throughout the plant.

Hydrophillic Molecules

Molecules attracted to water. Generally polar or uneven distrubution of charges (positive and negative). Soluble in water.

Polar Solvents dissolve…

Polar Solutes

Non Polar Solvents dissolve…

Non Polar Solutes

Water dissolves

Polar Solutes and Ionic Solutes

Hydrophobic Molecules in metabolism

Cell walls hydrophobic layer creates a barrier between the inside and outside of a cell

Water in metabolism

Substrates of the reactions and enzymes that act as catylysts dissolve in cytoplasm (an aqueous solution). This helps control the composition, function and interaction of cells. Water also helps dissolve sugars, salts and amino acids which provides organisms a medium for transporting materials to each cell from others.

Blood as a medium for transportation.

Blood is used to transport nutrients, hormones and waste to specialised organs. The majority of the cells (the plasma) uses water as a solvent to carry easily dissolved materials that tend to be hydrophillic. The non-polar parts are carried by the haemoglobin.

Buoyancy

Force that counteracts the force of gravity with the buoyancy increasing with the density of the water, allowing less dense materials to float such as ice and air. Cold water is the most dense, sinking due to the density.

Viscosity

Resistance to flow and related to the amount of energy needed to change a liquid’s shape.

Thermal Conductivity

The ability of a substance to transfer heat when there is a temperature difference

Specific Heat Capacity

How much energy is needed to raise the temperature of a substance

Solvent Proprties of Water

Water is called a universal solvent due to it being a dipolar molecule. If the force of attraction between ions and water is greater than the force of attraftion between oppositely charged ions, water can dissolve the substance.

Dissolve

Process of a solute mixing with a solvent to form a homogenous mixtures (a solution)

Dissolution

When ionic compounds are introduced to water, the partial positive hydrogen atoms will attract negative ions and partially negative oxygen atoms will attract positive ions. This will cause the water molecules to surround the ions and create hydrations shells which lead to the seperation of the solute particles and their uniform distribution throughout the solution

Covalent Compounds dissolving in water

They form intermolecular interactions with the dipolar water molecules. Some examples are oxygen, glucose and alcohol.

Osmosis

Movement of water molecules across a selectively permeable membrane from an area of lower solute concentration to an area of higher solute concentration. It’s a specific type of diffusion.

Reverse Osmosis

Water’s flow from a hypertonic to a hypotonic solution until the have the same concentration.

Hypertonic Solution

A solution with a higher solute concentration

Hypotonic Solution

A solution with a lower solute concentration

Dynamic Equilibrium

When two solutions are of equal concentration, otherwise referred to as an isotonic solution

Water movement from less to more concentrated solutions

Attraction between water and dissolved solutes causes water to move from regions of lower solute areas to regions of higher solute concentration

Crenated

State of an animal cell shrivelling and shrinking as a result of water loss

Plasmolysis

Shrinking of the cell membrane away from the cell wall in plant cells due to a loss of water from the cell

Lysis

When animal cells burst due to too much water in the cell

Cell in hypertonic solution

Net movement of water out of cell to surrounding solution. May become creanted (if animal cell) or undergo plasmolysis (if plant cell)

Cell in hypotonic solution

Net movement of water into cell which causes swelling and may cause lysis

Cell in isotonic solution

Equal movement in and out of the cell, creating a dynamic equilibrium, no changes in structure will occur

Macromolecules

Large molecules made up of monomers (becoming a polymer). Main classes of macromolecules are carbohydrates, lipids, proteins and nucleic acids. They are formed by condensation reactions where a polymer and water is created and broken down via hydrolysis by water molecules.

Carbohydrates.

Macromolecules essential to life. Made up of saccharides.

Monosaccharides

Simplest form of carbohydrates that can’t be broken down via hydrolisis. Pentose or hexose structures.

Glucose

2 isomers (alpha & beta) which have a difference in the orientation of carbon-1. The two alters in polysaccharude orientation with alpha glucose responsible for making up glycogen and starch. Beta glucose makes up cellulose. Soluble due the polarity of the -OH groups and allows easy transport by plasma in the blood. It’s a stable molecule and can be oxidised to produce atp by cellular respiration where it releases electrons.

Starch

A polysaccharide molecule composed of alpha glucose molecules. It’s the primary energy storage form in molecules with two types: amylose and amylopectin

Amylose

Linear polysaccharide with a linking through carbon 1,4 glycosidic bonds, and it forms a coiled structure. Overall it consists of 300-3000 glucose units

Amypectin

Highly branched structure with a primary link through 1,4 glycosidic bonds with branching from 1, glycosidic bonds. This branching structure allows for more complex 3d structure and storage of glucose. It makes up 80-85% of starch

Glycogen

Primary storage of glucose in animals as a branched polymer with the 1,6 glycosidic bonds every 8-12 units

Cellulose

Beta glucose built polysaccharide that’s in the cell wall of plants with a straight chain of alternating orientation. Forms long unbranched chains (microfibles) which gives the cell wall a rigid and sturdy structure and is helps the plant withstand osmosis

Glycoproteins

Proteins with 1 carb attaches and it has roles in cell-cell recognition, reception, as a ligand and in structural support. It acts as markers on the surface of cell which allows it to help in cells identifying each other, recieving signals, initiate signalling pathways by binding to protein receptors and contributing to structural integirty of cells and tissues by froming a part of the extracellular matrix

ABO Blood Groups

Based on presence of specific glycoproteins on red blood cell surface. Based on whether A &/or B antigen is present. Compatability based on recognition and interaction of glycoproteins.

Type A blood

When only A antigen present

Type B blood

When only B antigen present

Type AB Blood

When both A and B antigen present

Type O Blood

When no antigen is present

Lipids

Non-polar and low solubility when in water. Triglycerides, steroids and wax are all types of lipids.

Triglycerides

Common form of lipid from the condensation reaction of a glycerol unit with three fatty acid molecules that bond via ester bonds.

Phospholipid

Glycerol molecule with phosphate group and two fatty acids by ester bond and water.

Fatty Acids

3 Classifications based on # of double bonds in hydrocarbon chain; saturated, monounsaturated and unsaturated.

Saturated Fatty Acids

Straight chain with no double bonds, tight packing and is solid at room temperature.

Unsaturated Fatty Acids

1+ double bond. Not straight, has kinks/bends which prevents it from packing close and keeps it liquid at room temperature. Either mono or poly unsaturated. More double bonds means lower melting point. Either Cis or Trans.

Monounsaturated Fatty Acids

1 double bond and therefore 1 kink

Polyunsaturated Fatty Acidss

2+ double bonds and multiple bends

Cis-Unsaturated Fatty Acids

Naturally occuring

Trans-Unsaturated Fatty Acids

Not naturally occurring.

Phospholipid bilayer

Form cell membrane and is formed due to hydrophobic & hydrophillic regions.