Biology Unit 1 Semester Exam (Chapter 2-5)

Binary fisson

the method of cell replication used by prokaryotes

Asexual reproduction

a method of reproduction that produces genetically identical cells without the fusion of gametes (sex cells)

Cytokinesis

the division of the cytoplasm and formation of two daughter cells

Interphase

the first stage of the eukaryotic cell cycle which involves cellular growth and duplication of chromosomes. Composed of 3 phases: G1, S and G2.

Mitosis

the second stage of the eukaryotic cell cycle, which involves the complete separation of sister chromatids and nuclei.

Sister chromatids

the two identical halves of a replicated chromosome

What happens in interphase

DNA synthesis (replication)

What happens in G1 phase

-cell growth

-protein synthesis

-organelle replication

G1 checkpoint before S phase to ensure correct growth and inspects for DNA damage

What happens in S phase

DNA synthesis (or replication) occurs

What happens in G2 phase

-more growth

-prepare for mitosis

G2 checkpoint before mitosis to ensure correct replication

What happens in prophase

-condensation of chromatin to distinct chromosomes

-centrioles migrate towards opposite poles

-spindle fibres begin to form

-nuclear membrane breaks down and nucleolus disappears

What happens in metaphase

-spindle fibres fully form and attach to the centromere of each chromosome

-chromosomes guided towards the equator of the cell where they line up

M checkpoint confirms spindle fibres have correctly attached to the centromeres of chromosomes

What happens in anaphase

-spindle fibres contract, pulling the sister chromatids to opposite ends of the cell

What happens in telophase

-chromosomes pack together at either end of the cell and new nuclei membranes form (genetically identical)

-chromosomes decondense and spindle fibres disintegrate

What happens in cytokinesis

Animals: cleavage furrow develops and pinches the plasma membrane to form 2 cells

Plants: cell plate forms at the equator separating the 2 cells.

Apoptosis

the controlled death of cells in the body. Also known as programmed cell death

Intrinsic/mitochondrial pathway

the pathway of apoptosis which is initiated by the detection of internal cellular damage

Steps of the intrinsic pathway

1. cellular stresses initiate the mitochondria to release proteins that form pores in the mitochondria

2. cytochromes are released from the mitochondria

3. the release of cytochrome c into the cytoplasm initiates apoptosis

4. cytochrome c activates caspases

5. the caspases systematically dismantle the cell by fragmenting its DNA, cytoskeleton and golgi

6. phagocytic cells engulf the cell remnants

Extrinsic/death receptor pathway

the pathway of apoptosis which is initiated by the reception of extracellular death signalling molecules (often occurs to cells that have been infected by a virus/cancer cells)

Steps of the extrinsic pathway

1. Cytotoxic T cell (CTL) detects virally infect/cancer cell

2. CTL releases a pro apoptotic protein that binds to the death receptor on the target cell

3. a cascade of reactions occurs, causing caspases to be released within the cell

4. caspases (a protein digesting enzyme) digest the cytoskeleton and dismantle the cell in an orderly manner

5. the cell components are packaged into apoptotic bodies. These are engulfed by phagocytic cells.

blebbing

the bulging of the plasma membrane to form apoptotic bodies

apoptotic bodies

vesicles containing cell contents that are released from a dying cell during apoptosis and engulfed by phagocytes

necrosis

localised and premature cell due to a form of cell injury. It causes inflammation and rupture of the cell membrane spilling the cell contents and damaging nearby cells

Benign tumor

a tumor that lacks the ability to spread throughout other tissues and organs

Malignant tumor

abnormal cells with the ability to invade nearby tissue and migrate to other parts of the body (cancerous cells)

somatic

any cell that is not a reproductive cell (such as sperm and egg) somatic cells are diploid, meaning they contain 2 sets of chromosomes, one inherited from each parent.

Stem cells

undifferentiated cells with the capability of differentiating into specialised cells

Differentiation

the development of a stem cell into a specialised cell with a particular function

Specialised

cells which serve a unique, particular function

Properties of stem cells

-Self renewal: the capacity to replicate without disrupting their ability to differentiate by producing both a differentiated cell and a copy of themselves when they replicate

-Potency undifferentiated cells that can give rise to differentiated cells with a specific function

Totipotent

stem cells which can differentiate into any cell type.

Example: zygote

Pluripotent

Stem cells that can differentiate into multiple cell types.

Example: embryonic stem cells

Multipotent

stem cells which can differentiate into a limited number of specialised cell types belonging to a specific tissue or organ

Example: bone marrow

3 primary germ layers and examples of each

Ectoderm: neurons, skin cells, pigment cells

Mesoderm: skeletal muscle, smooth muscle, cardiac muscle, red blood cells, bone cells

Endoderm: stomach cells, pancreatic cells, liver cells

Process of DNA replication

1. The parent DNA molecule unzips using a cellular enzyme called helicase

2. Complementary DNA bases are added to each strand by an enzyme called polymerase

3. Two identical strands of DNA are produced.

Stem cell categories

Totipotent, Pluripotent, Multipotent, Unipotent

The Prime Minister's Umbrella

hydrophobic

having a tendency to repel from and be insoluble in water.

hydrophilic

having a tendency to be attracted to and dissolve in water.

amphiphilic/amphipathic

describes molecules with both hydrophilic and hydrophobic components

diffusion

the passive movement of molecules from areas of high concentration to areas of low concentration (down the concentration gradient)

isotonic

describes a solution with the same solute concentration as another solution.

hypertonic

describes a solution with a higher solute concentration when compared to another solution.

hypotonic

describes a solution with a lower solute concentration when compared to another solution

solute

a substance dissolved in the solvent (eg. sugar, salt)

solvent

a liquid in which a solute is dissolved, forming a solution

nucleus

the nucleus is surrounded by a double membrane. Its role is to protect and confine the genetic information (DNA) of the cell. Inside the nucleus is a smaller structure known as the nucleolus which is the site of ribosome production.

ribosomes

tiny structures made of ribosomal RNA (rRNA) and proteins that fold into a large and small subunit. Cells have many ribosomes, which either float freely in the cytoplasm or are attached to the rough endoplasmic reticulum. Ribosomes assemble the building blocks to make proteins.

Rough endoplasmic reticulum (RER)

a membranous chain of connected and flattened sacs which are coated with ribosomes. This allows the RER to synthesis and modify proteins. The RER typically surrounds, or is close to, the nucleus.

Smooth endoplasmic reticulum (SER)

a membranous chain of connected and flattened sacs which are not coated with ribosomes. The SER is responsible for the production of lipids in a cell.

Golgi apparatus (aka Golgi body)

stacked flattened sacs that are the sites of protein sorting, packaging, and modification for use in the cell or export. Protein-filled vesicles often fuse with or bud off from the Golgi apparatus.

Lysosome

a membrane bound vesicle that contains digestive enzymes. It is responsible for breaking down cell waste and toxins, acting like a garbage disposal.

Mitochondrion

An organelle with a highly folded inner membrane surrounded by a second outer membrane. Mitochondria are the site of aerobic cellular respiration, a chemical reaction that produces the ATP required to power cellular processes. They also contain their own DNA and ribosomes.

Chloroplast

A double membrane-bound organelle that contains flattened, fluid filled sacs that are the site of photosynthesis. Chloroplasts also contain their own DNA and ribosomes.

Vacuole

A membrane-bound sac that is used for water and solute storage. Vacuoles also play a role in maintaining plant cell structure.

Plasma membrane

The plasma membrane is a selectively permeable barrier between the intracellular and the extracellular environment. It is made of a phospholipid bilayer which is studded with many molecules.

Cell wall

A sturdy border outside the plasma membrane that provides strength and structure to plant, bacterial and fungal cells.

Vesicle

a small, membrane bound sac that transports substances into or out of a cell, or stores substances within a cell.

Cytoskeleton

a large network of protein filaments that start at the nucleus and reach out to the plasma membrane. The cytoskeleton is critical for maintaining shape and transporting vesicles around the cell.

Cytosol

the aqueous fluid that surrounds the organelles inside a cell.

MRS GREEN

Movement

Respiration

Sensitivity

Growth

Reproduction

Equilibrium

Excretion

Nutrition

Cell theory

1. all living things are made up of cells

2. cells are the smallest and most basic units of life

3. all cells come from pre-existing cells

homeostasis

the maintenance of a relatively stable internal environment in the body despite changes in the external environment.

prokaryotes

a group of single-celled organisms with no nucleus and a circular loop of DNA. (eg. bacteria, archaea)

eukaryotes

a group of single and multi-celled organisms with a nucleus and linear strands of DNA. (eg. animals, plants, fungi, protists)

Chlorophyll

a green pigment found in the thylakoids of chloroplasts. It is responsible for absorbing light energy in photosynthesis.

Animal cell does not have:

-chloroplasts

-cell wall

-large vacuoles

surface area: volume ratio

SA:V

a comparison of the amount of surface area per unit of volume. In Biology, SA:V influences temperature regulation, and a high SA:V leads to more effective transport into and out of cells.

phospholipid bilayer

a double layer of amphiphilic molecules that forms the primary component of cell membranes.

polar

describes a molecule with both a positive end and negative end. These tend to be hydrophilic.

nonpolar

describes a molecule without a clearly positive or negative end. These tend to be hydrophobic.

phosphate head

-made of a glycerol and phosphate group

-negatively charged, making it hydrophilic and polar

fatty acid tails

-made of long chains of carbon and hydrogen

-uncharged, hydrophobic and nonpolar

types of proteins in plasma membrane

-integral

-transmembrane (integral)

-peripheral

Integral protein

a protein that is permanently secured to the plasma membrane

Transmembrane protein

an integral protein that spans the entire plasma membrane

Peripheral protein

a protein that is temporarily attached to the plasma membrane

glycolipid

a phospholipid bound to a carbohydrate

glycoprotein

a protein bound to a carbohydrate

cholesterol

a steroid-alcohol that regulates fluidity in plasma membranes

carbohydrate (aka saccharides or sugars)

a class of biomacromolecule made from monosaccharide monomers consisting of carbon, hydrogen, and oxygen

protein

a class of biomacromolecule made of amino acid monomers folded into a 3D shape, consisting of carbon, hydrogen, oxygen, nitrogen and sometimes sulphur

Passive transport

the movement of molecules through a semipermeable membrane and down the concentration gradient, without an input of energy.

Active transport

movement of molecules across a semipermeable membrane that requires energy.

(eg. potassium ion)

Passive forms of transport

diffusion, osmosis, facilitated diffusion

Active forms of transport

active transport, bulk transport

Simple diffusion

Diffusion that doesn't involve a direct input of energy or assistance by carrier proteins.

Moves small, nonpolar, uncharged or hydrophobic molecules (eg. oxygen, hydrogen, carbon dioxide)

Facilitated diffusion

a type of passive transport where molecules move through a phospholipid bilayer with the aid of a membrane protein.

Moves large, polar, charged, hydrophilic molecules (eg. ions, glucose, amino acids)

Protein channel

a transmembrane protein pore in a phospholipid bilayer that selectively enables transport of large or polar molecules

Carrier protein

a membrane protein that undergoes conformational change to transport molecules across a membrane.

Osmosis

the passive transport of a solvent (typically water) through a semipermeable membrane from a region of low solute (high solvent) to a region of high solute (low solvent)

hypotonic solution for plants vs animals

Plants: turgid (normal)

Animal: lysed

isotonic solution for plants vs animals

Plants: flaccid

Animals: normal

hypertonic solution for plants vs animals

Plants: plasmolysed

Animals: shrivelled

Bulk transport (cytosis)

a type of active transport that uses vesicles to move large molecules or groups of molecules into or out of the cell.

Protein pump

a polypeptide that transports molecules across a membrane against its concentration gradient with the aid of ATP.

Exocytosis

a type of bulk transport that moves large substances out of a cell.

(eg. proteins made by the cell to be transported out, hormones, antibodies)

Endocytosis

a type of bulk transport that moves large substances into the cell.

(eg. bacteria)

Phagocytosis

endocytosis of solid material or food particles

"cell eating"

Pinocytosis

endocytosis of liquid or dissolved substances

organism

a living thing made up of one or more cells