AOS1 Flashcards
define apoptosis
genetically programmed cell death-in which the death of the cell is controlled by particular cell signals from either the inside or the outside of the cell
cell theory
The Cell Theory states:
- All organisms are composed of cells.
- All cells are derived from pre-existing cells (biogenesis)
- The cell is the smallest/basic organisational unit of any living thing.
Prokaryotes
Prokaryotes are all unicellular divided into 2 domains bacteria and archaea.
Prokaryotic cells have no membrane-bound organelles.
Prokaryotic cells have no true nucleus, but there is a nuclear region.
Their DNA is in the form of a single circular chromosome
Prokaryotic cells are much smaller than eukaryotic cells.
define solute, solvent and solution
Solute: substance that is dissolved
Solvent: liquid in which a substance dissolves
Solution: liquid mixture of solvent and solute
Define an impermeable, permeable and selectively permeable barrier
impermeable: no substance can cross it
permeable: any substance can cross it
selectively permeable: allows some substances to cross and can block others
define extremophiles
extremophiles are prokaryotic cells often found in extreme conditions such as high pressure and temperature
Define hypotonic,
Hypotonic-the surrounding solution of a cell that has a lower concentration of solutes and a higher concentration of free water molecules-the water moves into the cell causing it to swell
Surface area to volume ratio
as the size of an object increases the ratio between surface area and volume decreases
The rate at which materials enter and leave the cell depends on the surface area
what is the plasma membrane made of?
Carbohydrates, cholesterol, phospholipids and proteins
define polar
things that are polar are hydrophilic (attracted to water)-they have evenly distributed electrons
define non-polar
things that are non-polar are hydrophobic (repel water)-have unevenly distributed electrons
proteins in the plasma membrane
Peripheral-protein floating on the surface
Integral protein-imbedded in the fatty acid tail
Transmembrane protein-one side of the membrane to the other
define passive transport
transport that doesn’t require energy
define passive transport and examples
transport that doesn’t require energy for eg: diffusion, facilitated diffusion and osmosis
Define active transport
Active transport-is the movement of substances across membranes using energy from ATP. they goes against the concentration gradient from a region of lower concentration to a region of higher
define osmosis
The passive net movement of free water molecules through a partially permeable membrane, from a region of low solute concentration to a region of high solute concentration
define facilitated diffusion
passive movement of specific molecules down a concentration gradient via specific trans=port (carrier) proteins
cell replication in prokaryotes is called
binary fission-Simple process by which one parent cell divides in half to form two daughter cells
define simple diffusion
the passive movement of particles down a concentration gradient from a region of higher concentration to a region of lower concentration
what is the pressure that causes water to move along the osmotic gradient called
osmotic pressure
define Hypertonic
the solution has a higher concentration of solutes and a lower concentration of free water molecules than inside the cell-the water diffuses out of the cell causing the cell to shrivel
Define isotonic
the concentration of solutes in the solution is equal to the concentration of solutes inside the cell-water diffuses in and out of the cell at the same rate
what is the goal of mitosis
to make identical cells
name the phases of mitosis
prophase
metaphase
anaphase
telophase
why is mitochondria rippled?
because it increases the surface area of the membrane which means more ATP is produced
how do cells move large quantities of materials all at one time or move molecules that are too large to pass through the proteins in the plasma membrane into and out of their cytoplasm
bulk transport
describe and explain the two types of bulk transport
Endocytosis-describes the incorporation of substances from outside the cell into the cell in a membrane-bound vesicle. There are two forms of endocytosis: phagocytosis (consuming solids) and pinocytosis (absorbing liquids) .
Exocytosis-releases substances such as wastes for secretion from the inside of the cell to the outside. Occurs by fussion of a vesicle.
what is the structure of the plasma membrane called
fluid mosaic
Name the three membrane proteins
Peripheral protein-floating on the surface
Integral protein-embedded in the fatty acid tail
Transmembrane protein-goes from one side to the other
name the facilitated diffusion proteins
- channel proteins (small, charged and polar molecule)
- Gated channel protein(open and close in response to stimuli)
- Carrier protein(larger, polar and charged molecules)
active transport is performed by what proteins
carrier proteins aka pumps
describe the -sexual reproduction process prokaryotes undergo
Binary fission
1. Cell replicates all of its genetic material by copying the DNA using replication enzymes which begins at the spot called origin of replication
2. The two large circular strands of DNA move to opposite ends of the cell, plasmids are randomly distributed 3. The cell begins to grow 4. The cytoplasm itself begins to split and a new cell membrane and wall is formed
how quickly can bacteria divide
every 20 minutes
what are the two ends of nucleotides and what end can they be added on to
nucleotides have a 3prime (leading strand) and 5 prime (lagging strand)end. Nucleotides can only be added to the 3 prime end.
describe the process of cell division in eukaryotes
Interphase, followed by mitosis and lastly cytokenisis
describe the process of interphase
interphase is made up of 3 stages: G1; cell growth S: DNA synthesis (replication) each chromosome makes an exact copy of itself (these strands are known as chromatids) G2: post DNA synthesis cell double checks for any errors
Describe the 4 stages of mitosis
- prophase-chromosomes become visible as they shorten and thicken, they are held together by the centromere
- metaphase-the double stranded chromosomes line up in the middle of the cell
- Anaphase-centromere divides so that each copy of the chromosomes move to opposite ends of the cell as the tubules shorten
- Telophase-chromosomes become thinner and less obvious and a new nuclear membrane is formed
describe cytokinesis
is the division of the cytoplasm
how is cell divison controlled
there are three checkpoints
G1 growth checkpoint-checks to see if the cell is a healthy size if not the cell cycle stops (G0)
G2 synthesis checkpoint-sees if any errors are detected and proteins signal the cell to being mitosis
Mitosis checkpoint-proteins signal the cell to stop mitosis and enter the G1 phase once again
describe the two types of cell death
- necrosis-is the premature death of a cell that has been damaged through external forces such as trauma or infection, the cell swells and ruptures spilling its contents which may have adverse affects on surrounding cells
apoptosis-‘programmed cell death’. it allows the removal of cells without spilling their contents to the internal environment.
explain apoptosis in depth
Cell death occurs when the cell membrane shrinks, blebs form, DNA fragments and lysosomes empty their contents into the cell causing the cellular components to be broken down.
The dead cell is then consumed by phagocytes.
identify two characteristics of stem cells
Stem cells can self-renew-make copies of themselves
Differentiate-make other type of cells (specialised)
define Potency
a measure of how many types of specialised cells a stem cell can make
pluripotent stem cells
can make most types of specialised cells in the body-embryonic stem cells are mostly pluripotent
multipotent stem cells
can make many types of specialised cells in the body but not all types-tissue stem cells are multipotent
totipotent stem cells
can differentiate into all types of specialised cells in the body PLUS cells that are needed during embryo development
unipotent stem cells
can only differentiate into one type of specialised cell (spermatogonia cells can only differentiate into sperm cells)
cytoplasm
made of cytosol, it is where all of the activities of the cell take place
Plasma membrane
surrounds the cell, it forms the boundary between the cell contents and the extracellular environment
cell wall
surrounds only plant cells, located outside the membrane, it helps maintain the cells shape
Nucleus
In the cytoplasm, regulates all activities of the cell and contains the genetic materials (DNA)
Nucleolus
Located within the nucleus made of protein and RNA, it is where ribosomes are assembled
Rough ER
studded with ribosomes, involved in transporting proteins within the cell
Smooth ER
membranous tubules with no ribosomes, synthesises lipids and transports them
Golgi apparatus
membranous sacs, involved in modifying, packaging and transporting proteins received from the ER (exocytosis)
Lysosomes
sac containing enzymes, bud off the golgi apparatus and release enzymes that cause cell death
mitochondria
are mostly present in metabolically active cells, the site of aerobic respiration with inner membranes
plastids
in the cytoplasm of plant cells and protista
Chloroplast
contains chlorophyll and is the site of photosynthesis
Vacuole
liquid-filled sacs in the cytoplasm which store materials
centrioles
in the cytoplasm of animal cells, part of the cytoskeleton, they support microtubules that move chromosomes during cell division
zygote
diploid cell resulting from the fusion of an egg and sperm-it is totipotent
Embryonic stem cells
un-differentiated and are found in the blastocyst they are pluripotent
gastrula
has three primary layers of cells called germ layers
Groups of cells in an embryo
Ectoderm-outer layer
Mesoderm-middle layer
Endoderm-inner layer
The stem cells within these layers can only become particular things
purposes of apoptosis
- maintain the number of adult cells
- defend against damaged or dangerous cells
- the transformation of embryonic tissues (fingers)
Polypeptide
A long, chain-like molecule consisting of many amino acids linked together.
size of a prokaryotic cell
1-10um
size of eukaryotic animal cells
10-20um
size of eukaryotic plant cells
30-50um
List 8 organelles and structures common to both plant and animal cell
nucleus, plasma membrane, ribosomes, mitochondria, Golgi apparatus, endoplasmic reticulum (rough and smooth), cytoskeleton, vacuoles (vary is size and function)
define diffusion
Is the tendency of molecules to dispense until they are evenly distributed in the available space (reached equilibrium)
define turgid cell
A turgid cell is a cell that has turgor pressure. A plant cell that is placed in a hypotonic solution would cause the water to move into the cell by osmosis, resulting in large turgor pressure being exerted against the plant cell wall
phospholipids have what kind of fatty acid tails
hydrophobic
small and nonpolar molecules can cross the plasma membrane via what
simple diffusion
oxygen and carbon are able to cross the phospholipid bilayer by what process
diffusion
proteins enter the cell by what process
Endocytosis/Phagocytosis
high SA:V means what?
The higher SA:V ratio, the faster the rate of diffusion which thus increases efficiency of nutrient absorption and waste expulsion.
how to increase the cell SA: V
1) Cell Compartmentalisation
2) Flattened Shape
3) Plasma Membrane Extension
common cell features
- Plasma Membrane
- Cytoplasm
- DNA
- Ribosomes
In binary fission what happens to the cytoplasm
There is an equal division of the cytoplasm.
3 germ layers in the gastrula
ectoderm-outer
mesoderm-middle
endoderm-inner
IPS
induced pluripotent stem cells-reversible cell differentiation
