SACE Stage 2 Biology: Cells

Cell theory: All living things are composed of _________ developed over many years and is strongly linked to the ________________. All cells are made up of an outer _________ enclosing a fluid known as the ________________. This cytoplasm consists mainly of water and contains a variety of smaller structures that are collectively called _______________.

cells, microscope, membrane, cytoplasm, organelles

All living things are composed of __________ and _________ products.

cells, cell

A cell contains the genes used as instructions for _________, _______________ and _______________.

growth, functioning, development

The cell is the functioning unit of _____; all of the chemical reactions of life; all chemical reactions take place in cells.

life

The membrane surrounding a celll, the ____________ ______________, forms the boundary that seperates the living cell from its _________-__________________ surroundings. The membrane is about _____nm thick, it selectively controls the movement of materials into and out of the cell. It is responsible for ________-cell recognition, and is a dynamic structure with distinct inside and outside faces. The plasma membrane is common to all cells and forms their ___________ __________. Bacteria, fungi and plant cells have a ________ _________, a structurally distince feature and lies ______________ the plasma membrane.

plasma membrane, non-living, 8 cell, outer limit, cell wall, outside

The accepted model for the structure of the ____________ ______________ is the __________ _____________ _________. In this model there is a double layer of _________________ (fats) which are arranged with their _________ tails inwards. THe double layer of lipids is quite _______, with __________ floating within it. _________proteings, __________lipids, and _____________ are also an integral part of the membrane structure.

plasma membrane, fluid mosaic model, phospholipids, hydrophobic, fluid, proteins, glyco, glyco, cholesterol

_________ fulful a role in ______ and ___ between cells. This allows '________' cells to form tissues and organs. Some membranes are involved in _________ _____________.

membranes, recognition, communication, like, membrane transport

Membranes are also found within ___________ cells as part of the structure of ______________ ____________, such as vacuoles and mitochondria. The membrane of organelles have the same basic structure as the cell-surrounding plasma membrane.

eukaryotic, membrane organelles

Animal and plant cells have many common organelles, as well as features specific to each. An animal cell has the specialised features of a __________ and _______________, while plant cells have the specialised features of ___________, a _______-_________, and starch granules.

lysosome, centrioles, chloroplasts, cell wall

NUCLEUS: Located not necessarily in the centre of the cell. It is surrounded by a _____ ___________ and encloses the _________. The envelope has a __________ membrane perforated by pores approximately 100nm diameter. The function of the nucleus: It contains most of the cell's ____________ __________, which _______________ the activities of the cell.

nuclear envelope, chromatin, double, genetic material, regulates

NUCLEOLUS: Located within the __________ (there may be more than one within specific organisms). It is a prominent structure appering as a mass of darkly stained granules and fibres adjoining part of the ___________. Its function is to synthesise _______, and assemble _________________ subunits.

nucleus, chromatin, rRNA, ribosomal

MITOCHONDRIA: Located in the _________. Structure: rod/cylindrically shaped, occurring in large numbers. Bound by a __________ membrane; inner layer is extensively folded to form partitions called _________ (containing some DNA). It has a jellylike internal substance known as the ________. Its function is to produce ________ as the cellular _________ site.

cytoplasm, double, cristae, matrix, ATP, respiration

CHLOROPLASTS: Located in the ___________ of plant leaf/occasionally stem cells. Their structure is that of specialised ___________ containing __________. It has two outer membranes separated by a narrow inter-membrane space. Inside are stacks of flattened sacs (___________), stacked together as ________, which contain some DNA. It is the site of _______________.

cytoplasm, plasmids, chlorophyll, thylakoids, grana

VACUOLES AND VESICLES: Located in the _____________. Structure: Both membrane-bound sacs; __________ are larger. Food vacuoles in animal cells were formed by ___________ of food particles. _____________ vacuoles of freshwater protists pump excess water from the cell. The _____________ vacuole of plants provides cell volume and stores inorganic ions and ______________ wastes.

cytoplasm, vacuoles, phagocytosis, contractile, central

GOLGI APPARATUS: Located in the _______, associated with the endoplasmic reticulum. Structure: Stack of flattened membranous sacs called _____________. Function is the ___________ of proteins and lipids received from the ER. __________, packaging, and ________ of proteins and lipids. ________ of these materials in _______ through the cell. Manufactures some certain macromolecules.

cytoplasm, cisternae, modification, sorting, storage, vesicles

SMOOTH ENDOPLASMIC RETICULUM: Located in the ___________ as part of the ___________ system. Structure: system of membranous tubules similar in apperance to the RER, without _______________. Its function is the ____________ of lipids, phosopholipids and steroids. It also does _____________ metabolism, and _______ of these materials through the cell. It also ___________ drugs and poisons.

cytoplasm, endomembrane, ribosomes, synthesis, carbohydrate, transport, detoxifies

ROUGH ENDOPLASMIC RETICULUM: Continuous with the ____________ __________ and extending to the cytoplasm as part of the endomembrane system. Structure: Complex system of membranous tubules studded with ________. Connected to the SER but structurally and functionally distinct from it. The function is the _______, folding and _________ of proteins. ________ of proteins through the cell and __________ production.

nuclear membrane, ribosomes, synthesis, modification, transport, membrane

RIBOSOMES: Free in the ____ or bound to the RER. Made up of _______ and _________ and composed of two subunits, a larger and a smaller. Synthesis of _____________.

cytoplasm, rRNA, protein, polypeptides

LYSOSOMES: Free in the ________. Single-membrane bound sac of _____________ enzymes. Lysosomes bud off the _________ ___________. Their function is intracellular digestion of macromolecules and recycling of cellular components (__________). Low internal pH maintained by H+ pump in the lysosomal membrane.

cytoplasm, hydrolytic, autophagy

CENTRIOLES: Located in the ___________, as part of the __________. Usually next to or close to the nucleus. Structure: Found as a pair, each composed of ___ sets of triplet microtubules arranged in a ring. They are involved in organising microtubule assembly (______________ ______________) but not essential as they are _______ from the cells of higher _____.

cytoplasm, cytoskeleton, 9, spindle formation, absent, plants

CYTOSKELETON: Located in the ___________. It is a dynamic structure of _________, _______________ and intermediate filaments. Its function is the shape, and mechanical support for the cell. Regulation of cellular activities, e.g. guiding, secretory vesicles. Especially important in _________ cells. Involved in cell movement (_________).

cytoplasm, microtubules, microfilaments, animal, motility

All organisms require _______ to grow, reproduce, move and carry out fundamental maintenance and repairs. Organisms capable of producing their own energy are ________. __________ autotrophs convert light energy into chemical energy. ___________ autotrophs derive their energy from inorganic sources. Some bacteria are _______________.

energy, autotrophs, photosynthetic, chemosynthetic, chemoautotrophs

_____________ is the action of transforming _____________ energy into __________ energy. It produces _________ for use later down the food chain, and _______, essential for the survival of advanced life forms. Photosynthesis takes place in membrane-bound organelles known as ___________.These are filled with a green pigment, ____________. The chloroplast is enclosed by an envelope consisting of two membranes separated by a very narrow inter-membrane space. These membranes also divide the interior of the chloroplasts into compartments: the _______ (fluid) outside the thylakoids, and the ______, which are flattened sacs, in some places stacked into structures called ______.

photosynthesis, sunlight, chemical, energy, oxygen, chlorophyll, stroma, thylakoids, grana

Chloroplasts contain________ and also ___________, used to synthesise some of the proteins within the chloroplast. The photosynthetic pigments of the ________ in higher plants absorb blue and red light. Plant leaves also contain ________ pigments, which capture light outside the wavelengths captured by chlorophyll.

DNA, ribosome, chloroplasts, accessory

___________ __________ is a catabolic, energy-yielding pathway. The break down process by which organisms break down energy-rich molecules such as _____, releasing energy for the synthesis of ________ and requires ________, _________ does not.

cellular respiration, glucose, ATP, oxygen, anaerobic

________ is the first step of cellular respiration. It converts ________ to ________. It occurs in the cell ______. It produces cellular energy sources such as ATP and NADH for anaerobic and aerobic respiration. It produces ______ for use in the ______ _________ _________, and intermediate carbon compounds, which can be removed for other cellular purposes. The yield of glycolysis is __ ATP, __ NADH + H+, __ pyruvate (4ATP produced, but 2ATP consumed)

Glycolysis, glucose, pyruvate, cytosol, pyruvate, citric acid cycle, 2, 2, 2

After glycolysis, the ___________ reaction occurs in the __________ _________, and forms acetyl coenzyme A from the pyruvate.

transition, mitochondrial matrix

The _____ _______, also known as the citric acid cycle. Two turns of he krebs cycle are required to completely oxiidise one gllucose molecule. Two turns yields _ CO2, __ ATP, __ NADH + H+, and 2 FADH to produce 34 ATP. THe cycle yields a small amount of energy in the form of _____, but a lot of potential eneergy in the form of reducing power in NADH and FADH. The energy value from the krebs cycle is realised when the NADH and FADH2 molecules (which act as electron carriers) are used to generate ATP in the next stage of glucose metabolism.

krebs cycle, 4, 2, 6, ATP

The electron transport chain: H2 is ________ to water using ________. Energy is released as ATP. Glucose metabolism is ___________ (it releases energy).

oxidised, oxygen, exergonic

All organisms can metabolise glucose __________ (without ________) using ________ in the cytoplasm. Fermentation pathways for glucose metabolism do not use oxygen as a final electron receptor. The energy yield from fermentation is _____, and few organisms can obtain sufficient energy for their needs this way. An alternative electron acceptor is required in the absence of oxygen, or __________ will stop. In _____ ____________ the electron acceptor is _______. During __________ ___________ ________ the electron acceptor is pyruvate intself and the end product is lactic acid.

anaerobically, oxygen, glycolysis, low, glycolysis, alcoholic fermentation, ethanal, lactic acid fermentation

Glycolysis can continue in the absence of oxygen by reducing pyruvate to ______ _______. This process is called lactic acid ______________. Lactic acid is _____ and this pathway cannot continue indefinitely. Liver converts the lactic acid back into a harmless respiratory intermediate. Lactic acid fermentation occurs in the skeletal muscle of mammals.

lactic acid, fermentation, toxic

Yeasts respire ________ when oxygen is available, but can use alcoholic fermentation when it is not. These organisms are called ________ ___________. At ethanol levels above 12-15%, fermentation is toxic to the yeast cells. It cannot be used indefinitely. The root cells of plants also use fermentation as a pathway when oxygen is unavailable. ___________ is ________ and must be converted back to respiratory intermediates and respired anaerobically to reduce its levels. ___________ ___________ is carried out by yeasts and some bacteria.

aerobically, facultative anaerobes, ethanol, toxic, alcoholic fermentation

______________ ____________ ________________ occurs when organisms/tissues can produce ATP using aerobic respiratory pathways when oxygen is present, and ___________ pathways if oxygen is absent.

facultative anaerobic metabolism, anaerobic

Some organisms respire only in the ________ of oxygen; oxygen is toxic to them. These are _______ ___________. Some are _____________ _____________, and the by-products of their metabolism are toxic and can cause diseases.

absence, obligate anaerobes, bacterial pathogens

___ is the universal energy carrier for cells. ATP can release its energy quickly by hydrolysis of the terminal phosphate, catalysed by _________. Once it releases the energy it become ______ (a low charged molecule that can be recharged by adding _____________)

ATP, ATPase, ADP, phosphate

The membrane surrounding a cell (________ membrane), forms the boundary that separates the living cell from its non-living surroundings. Although the plasma membrane is 8nm thick, it __________ controls the movement of ___________ in and out of the cell, and is responsible for cell-cell _______________, and is a dynamic structure, wth distinct inside and outside faces.

plasma, selectively, substances, recognition

The plasma membrane is ____ __________ to certain molecules. Channel and ______ _________ are involved in selective transport of small molecules and ions across the membrane. _______ _______ (e.g. proteins) are transported by ________ (formation of membrane-bound vesicles or vacuoles)

partially permeable, carrier proteins, large molecules, cytosis

__________ is a passive transport process. It does not require energy to occur. It describes the movement of molecules from regions of ____ concentration to _____ concentration along a __________ __________. Diffusion usually occurs across _______ ________ membranes. In any type of diffusion, each diffusing molecules moves along its own concentration gradient. An _____________ is reached when the net concentration of molecules in each side of the membrane are equal. At this point, ______ _________ stops. Two-way diffusion is possible.

diffusion, high, low, concentration gradient, equilibrium, net movement

_________ diffusion occurs when a substance is aided across a membrane by _________, lipid soluble molecules that increase the permeability of cellular membranes to specific ions, and act as channel formers that introduce a hydrophilic pore in the membrane through which ions may pass. it _________ increases the diffusion rate of specific molecules, and does not require energy because the molecules are not moving against their concentration gradient. It occurs when a higher diffusion rate is desirable.

facilitated, ionophores, selectively

There is a physical limit for the size of a cell, with the effectiveness of _______ being the controlling factor. This is because a small organism has a large ________ ________ relative to its ________. This makes __________ effective. As the organism increases in size, diffusion becomes less effective. Multicellular organisms, overcome small cell size by evolving various adaptive features.

diffusion, surface area, volume, diffusion

The ______________-__________ to ___________ relationship had important implications for processes involving transport into and out of cells across membranes. As cell size increases; its volume increases at a _____________ rate than the surface area, there is _________ surface area, so the surface area:volume ration decreaseses, and large cells have difficulty exchanging materials of adequate rates.

surface-area, volume, faster, less

____________ is defined as the net movement of water molecules across a partially permeable membrane from a region of _____ to _________ concentration. Water movements are expressed in terms of water, and solute potential - water molecules always move _________ regions of more negative water potential. It provides the main means by which water is transported into and out of cells. The net _________ of water movement in cells can be predicted on the basis of the water -_________ of the solutions involved. It is affected by the same factors as ______________ is.

osmosis, high, low, towards, movement, potential, diffusion

Water _________________ of a solution describes the tendency for water molecules to enter/leave a solution by ______________. Pure water has the ____________ water potential of zero. Dissolving solute into pure water lowers the water potential (makes it more negative). Water potential is determined by two components: ___________ potential and _____________ potential.

potential, osmosis, highest, solute, pressure

____________ potential: The hydrostatic pressure to which water is subjected (usually positive), sometimes called ____________ or wall pressure.

pressure, turgor

______________ potenital measures the reduction in water potential due to the presence of solutes. It is _____________ and sometimes known as osmotic ________/pressure

solute, negative, potential

Animal cells lack a rigid cell wall, and may change shape according to the cellular environment. The conditions are ____________, ____________ and ____________.

isotonic, hypotonic, hypertonic

Isotonic: When extracellular environment has the _____ water potential as the cell; cell maintains its usual shape and form.

same

Hypotonic: The water potential of the extracellular environment is less ___________ than that of the cell. In this environment, water will ______ the cell. This will eventually cause cell _______ (cell bursting) in an animal cell.

negative, enter, lysis

Hypertonic: The water potential of the extracellular environment is _______ negative than that of the cell (cell will ________ water). This process is known as ________ in animal cells, or _______ in plant cells. A cell will lose its ability to function if it becomes severely dehydrated.

more, lose, crenation, plasmolysis

____________: plant cells lose water, membrane shrinks away from the cell, _______ collapses, and cell becomes flaccid (Water potential = 0). Full plasmolysis is irreversible; cell cannot recover by taking up water.

plasmolysis, vacuole

__________ transport requires energy expenditure because materials must be moved ______ their concentration-gradient. It is performed by specific carrier proteins in the membrane. These harness the energy of _____ to pump molecules from a low concentration to a high concentration. When ATP transfers a phosphate group to the carrier protein, the protein changes its shape so that the bound molecule can move across the membrane.

active, against, ATP

The _________-potassium pump is a protein in the membrane that exchanges sodium ions for potassium ions across the membrane. ATP is the energy source for the exchange. The ___________ balance of Na+ and K+ across the membrane creates large gradients in _______ concentration, which can be used to drive other active transport mechanisms.

sodium, unequal, ion

Proton pumps use ATP's energy to move _______ ions from inside the cell to the outside. This creates a difference in the protein concentration either side of the membrane, leaving the inside of the membrane negatively charged. The _____ difference created can be coupled to transport other molecules across the membrane.

hydrogen, potential

Coupled/cotransport: Plant cells use the ___________ gradient created by proton pumps to actively transport nutrients into the cell. For example, the return of H+ is coupled to the transport of sucrose into the phloem cells. Sucroses rides with the H+ as it diffuses down the concentration gradient maintained by the proton pump.

hydrogen

________ is a form of active transport involving the formation of membrane-bound vesicles or vacuoles. Regions of the plasma membrane infold ___________ or out fold ______________ to transport substances across the membrane. Forms of cytosis include endocytosis and _____________.

cytosis, invaginate, evaginate, exocytosis

________ is the incorporation of substances from outside the cell into the cell as a vesicle or vacuole. During this the plasma membrane ____________ across the molecules to be transported into the cell. _____________ is the engulfment of solid particles, ___________ is the engulfment of liquid particles, and ______________ ___________ is the engulfment of specific particles according to membrane receptors.

endocytosis, invaginates, phagocytosis, pinocytosis, receptor mediated

__________ releases substances from the inside to outside of a cell. IT occurs by fusion of a vesicle membrane with the plasma membrane. Vesicle contents are then released to the outside of the cell.

exocytosis

Glucose is the main fuel for _______. ____________________ can also be used as a feed substrate, but must first be converted into __________. During glycolysis, one _______ molecule (6-carbon sugar) is converted into 2 ____________ (3 carbon acid) molecules. Several intermediate products are produced, which may be utilised at any time in other cellular processes.

glycolysis, glycogen, glucose, glucose, pyruvate.

The energy released from the electrons is used to transport H+ across the membrane. This results in the establishment of a _________ gradient. The proton gradient couples the electron transport to ATP synthesis by a process known as _____________. It takes place in the inter-membrane space of the mitochondria and is the process where electron transport is coupled to ARP synthesis. Energy from the electron transport chain is used to move protons _______ the concentration gradient. The protons move from the ______ into the inter-membrane space between the two membranes. The protons flow back down their concentration gradient via an enzyme called ________synthase. This molecule uses the energy released from the H+ flow to produce _____.

proton, chemiososmosis, against, matrix, ATP, ATP

______________ is the physiological constancy of the body despite external fluctuations. It is maintained by the organ systems.

homeostasis

Prokaryotic cells come in a variety of shapes and sizes. They have no defined nucleus, and often have _________, and have a cell membrane inside a cell ________. They all divide in the same way. The nuclear material attached to the cell _______________.

flagella, wall, membrane

Cell ____________ is the process where a parent cell _____ into two daughter cells. There are two types of cell division. Mitosis occurs in _______ cells. Meiosis occurs in the ____ organs and produces sex cells (_____________).

division, divides, somatic, sex, gametes

All eukaryotic cells contain a ____________, also called the _____________ organising centre. Within a centrosome of animal and algal cells, there is a pair of ____________. During cell division, the centrosome divides and the centrioles replicate, producing two centrosomes, each with its own pair of centrioles. The two centrosomes each move to opposite ends of the nuclesus. Each then produces _________. These form the _________ responsible for separating the replicated chromosomes itno two daughter cells. Plant cells have centrosomes without centrioles.

centrosome, microtubule, centrioles, microtubules, spindle

Mitosis: During mitosis, an existing ________ cell divides into two new _______ cells. The cells are _________ identical. There is no change in chromosomal number. Cells are _______, containing two sets of chromosomes. Mitosis is associated with the growth and repair of _________ cells.

parent, daughter, genetically, diploid, somatic

________ accounts for 90% of the cell cycle. The 3 stages of interphase are: G1 - the cell grows and develops, S - the cell duplicates its genetic material, G2 - the nucleus is well defined, the chromosomes condense.

interphase

Early prophase:
- nuclear membrane disintegrates
- nucleolus disappears
- the ___________________ condense into visible and
chromosomes.

chromatin

Late prophase:
- the chromosomes continue to coil and appear as double
chromatids.
- the chromatids are each joined by a ____________.
- The centrosomes move to opposite poles of the cell. As
they do so, they form the mitotic spindle between the
poles.
- the _____________ mature and attach to the spindle

centromere, kinetochores

Metaphase:
- the chromosomes become aligned at the equator of the
cell.
- the _______ plate is an IMAGINARY plane equidistant
between the two poles. Kinetochores are disc-like
structures to which the spindle fibres attach.
- the spindle fibres are made up of microtubules and
associated with proteins, joined at the ends ( The spindle
____)

metaphase, poles

Early Anaphase:
- In anaphase, the chromosomes are pulled to opposite
poles of the cell.
- The centromeres divide, freeing the two sister-chromatids
from each other.
- Each chromatid is now considered a _________
- The spindle fibres begin moving the onece-joined sisters
to opposite poles.

chromosome

Late _____________:
- the kinetochore microtubules shorten as the
chromosomes approach the poles.
- At the same time, non-kinetochore microtubules elongate the cell.
- By the end of anaphase, the two poles of the cell have
equivalent and complete colections of chromosomes.

anaphase

______________:
- The non-kinetochore microtubules continue to elongate
the cell
- The daughter nuclei begin to form at the 2 poles of the
cell where the chromosomes have gathered.
- The NUCLEOLI REAPPEAR and the chromatin becomes
less condensed.

telophase

Cytokinesis is well under way by the end of telophase, so that the appearance of two new daughter cells follows shortly after the end of mitosis.
- In plant cells, the cell plate forms where the new cell wall will form.
- In animal cells, a __________ furrow pinches the cell in two.

cleavage

Mitosis in plant cells occurs only in regions of _________ tissue. The meristematic tissue is located at the _____ of every ______ and ___________. In contrast, mitosis can occur throughout the body of growing animal.

meristematic, tip, stem, root

Meiosis occurs in ______ only. It results in cells with half the chromosome number (n). It results in two __________ cells. This variation is due to crossing over and _________ assortment. The daughter cells are not capable of further division, but are capable of fusing with another cell. It results in 4 cells.

gonads, different, independent

Sex is a process which changes the relationship between different elements in the genome without the introduction of genetic new material. __________: A process by which the number of organisms is changed (usually increased). Sex is a change in the ____ of cells or individuals, reproduction is a change in the _______ of cells or individuals.

reproduction, state, number

Asexual reproduction is a change in the number of cells/individuals without a change in the genetic state of the cells. It has a cellular basis of ________. Examples of asexual reproduction include; budding, binary fission, regeneration, parthenogenesis and plants' vegetative reproduction.

mitosis

_________ reproduction combines reproductive products from different individuals. It has the advantage of producing unique _____ combinations in different individuals. It has a disadvantage of losing __% of your genes every generation, cost of combining your genes with an unknown genome. It is good in variable environment.

sexual, genetic, 50

Triggers for cell division include;
- size
- environmental signals (act via certain proteins)
- contain nutrients present
- lack of _________ with other cells
- some cells need to be attached to a ________.

contact, substrate

Normal mammalian cells: The availability of nutrients, growth factors an a substrate for attachment limits cell density to a single __________. Cancer cells continue to divide well beyound a single layer, forming a clump of overlapping cells.

layer

Checkpoint 1 (___ phase):
Growth factors:
- proteins secreted by other cells bing to receptor
molecules in the cell membrane.
- A message is relayed into the cell (to the cell cycle control
mechanism) via relay proteins.
- This message allows the cell to proceed past the first
checkpoint

G1

Checkpoint 2 (___ phase)
- CRITICAL CHECKPOINT: occurs right before the cell begins __________. Two types of proteins regulate this checkpoint, an enzyme and _______ which activates the enzyme. They form _____. An increase in this STARTS ___________>

mitosis, cyclin, MPF, mitosis

Checkpoint 3: During __ phase.
- At the end of metaphase and the start of _______.
- Decrease in _____ allows anaphase to begin and hence
completion of the cell cycle.

m, anaphase, MPF

If a cell receives a 'go-ahead' signal at the G1 checkpoint, the cell continues on in the cell cycle. If a cell does not receive a go-ahead signal at the G1 check point, the cell exits the cell cycle and goes into G__, a ______-dividing state.

0, non

___________ are substances made in one place which act in another. _______ in plants cause plant cells to divide rapidly leading to death (weed-killers). Hormones ________ cell division. E.g. Follicle-stimulating hormone (FSH) stimulates the development of follicles in ovaries and testes. ________ controls the production of red blood cells.

hormones, auxins, regulate, erythropoietin

Cancer is caused by _______ of genes which control and regulate cell division. A change (or mutation) in the DNA sequence often leads to the onset of cancer.

mutations

________________ are environmental factors that increase the rate of mutation. ______________ are environmental factors that increase the rate of cancer.

mutagens, carcinogens

Glucose is a _________. There is _________ in a cell wall.

monosaccharide, cellulose