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cell flash cards
Flashcards do conjunto (83)
- 1what is the cell theory?All living organisms are made from cells or the products of cells
All cells arise from pre-existing cells
All cells contain hereditary material - 2when was the earth formed?4.5 billion BP (before present)
- 3when were Prokaryotic Cells formed?3.5 billion BP
- 4What was the first Endosymbiotic event?The first endosymbiotic event occurred when a eukaryotic cell engulfed a prokaryote. This process, known as primary endosymbiosis, created the mitochondrion.
Chloroplasts likely evolved when a eukaryotic cell containing mitochondria engulfed a photosynthetic cyanobacteria - 5when did Eukaryotes form?1.5 billion BP
- 6What are the 7 characteristics of living things?
- 7What does Movement mean in relation to the characteristics of living things?have a complex organised structure
- 8What type of cell is this: Prokaryotic or Eukaryotic?Prokaryotic
- 9What type of cell is this: Prokaryotic or Eukaryotic?Eukaryotic
- 10What are the different types of Eukaryotic cells?Animals, Fungi and plants
- 11What are the different types of Prokaryotic cells?Bacteria and Archaea
- 12How do you differentiate between Prokaryotic and Eukaryotic Cells?Prokaryotes are cells that lack a nucleus and membrane-bound organelles. They are smaller and simpler and include bacteria and archaea. Eukaryotic cells have a nucleus and membrane-bound organelles, which help to organise and compartmentalise functions in the cell.
- 13How do you differentiate between Animal, Fungi and Plant Cells?Animals have no cell walls; fungi have cell walls containing chitin; Plants have cell walls containing cellulose. Chloroplasts are absent in both animals and fungi but are present in plants.
- 14What cell is this?Plant Cell
- 15What cell is this?Animal Cell
- 16What cell is this?Fungi Cell
- 17What cell is this?Fungi Cell
- 18What cell is this?Animal Cell
- 19What cell is this?Plant cell
- 20what is Endosymbiosis?The term symbiosis describes a pattern of living in which two organisms help each other for mutual benefit. ENDO means inside = ‘living inside for mutual benefit’ - It is thought that the evolution from Prokaryotes to Eukaryotes occurred through an ENDOSYMBIOTIC EVENT
- 21what are the main organelles in a cell?nucleus
– nucleolus
– mitochondrion
– chloroplast
– vacuole
– Golgi body (including vesicles)
– endoplasmic reticulum (rough and smooth)
– ribosome
– lysosome - 22what is the nucleasNucleus (nuclei = plural)
•This is the structure (the kernel) after which the Eukaryotes are named.
•The nucleus controls cell function (through its control of enzyme production).
•It is surrounded by a double membrane called the nuclear envelope, which contains nuclear pores.
•It contains chromatin (DNA coiled around
proteins). During cell division the chromatin
condenses to form chromosomes (short thickrod like structures)
•Outer membrane connects to the Rough Endoplasmic Reticulum (RER)
•The Nucleoli (singular – nucleolus) are darker spots in the nucleus which are the site of ribosomal RNA (rRNA) synthesis.
Nucleus - 23whats a Mitochondrion ?Mitochondrion (mitochondria = plural)
•A cigar shaped organ which has a smooth outer membrane and a folded inner membrane (the folds are called cristae) up to 10μm in length
•the latter stages of aerobic respiration
occur in the mitochondria (i.e. it is the site of most energy production in the cell). This
explains why some cells, such as muscle
cells, which require a lot of energy, have abundant mitochondria.
•Mitochondria may have evolved from free
living aerobic bacteria which became
internal symbiotes – through endosymbiosis.
•They contain DNA which resembles
prokaryotic DNA more than eukaryotic. - 24what is a chloroplast?•Organelle containing chlorophyll found in plants and algae.
•Surrounded by two membranes which are positioned close to each other
•Inside the chloroplasts are many flattened sacs called thylakoids which may be arranged in stacks called grana. The fluid surrounding the sacs is called the stroma.
•The thylakoids contain chlorophyll. Thylakoids are stacked in grana. Lamellae acts as a bridge to keep the grana separated so they don’t clutter together.
• The chloroplast is the site of photosynthesis in the cell. i.e. The process of trapping light energy to produce glucose and O2 from CO2 and H2O.
•Some plants may contain other coloured pigments instead of chlorophyll, e.g. red or brown algae - 25what is the Endoplasmic reticulum?Two varieties of Rough & Smooth
•A network of membranous tubules and sacs
•Channels molecules through the cell's interior, like a little highway
•Extensions of the nuclear membrane
•Two distinct connected, regions
that differ in structure and function
Smooth ER & Rough ER - 26what is the Rough endoplasmic reticulum?Structure
• Flattened series of membranes, continuous with the nuclear membrane, covered with ribosomes
Function
• Isolates proteins that are to be secreted by the cell and transports them to the Golgi body
• It allows the packaging of polypeptide chains inside the ER into vesicles which
are to be transported within the cell - 27what is the smooth Endoplasmic reticulum?Structure
• Consists of tubular membranes without ribosomes.
• This series of membrane bound, inter-connected sacs is found throughout the cell and connects the space between the nuclear membrane to the outside environment
Function
• Produces and secretes lipids and
phospholipids (e.g. Lipids in membranes
and steroid hormones) - 28what is the Golgi body?Structure
• stack of flattened sacs made of smooth membrane
Function
• The Golgi is involved in packaging and secretion and Modification of proteins.
• These molecules are often proteins produced in the ER
• Vesicles bud off from the Golgi body and migrate to the cell membrane where they fuse with it and release their contents to the extracellular environment.
• This process is known as exocytosis - 29what is a Ribosome?They are not membrane-bound organelles, but they are found in all cells.
• Ribosomes are the site of protein synthesis.
• They are made of large and small subunits that connect to hold a mRNA molecule while it is being translated to form a polypeptide chain of amino acids.
• Ribosomes facilitate the formation of peptide bonds between amino acids.
• Located ‘free’ in the cytoplasm, and ‘bound’ to the outside of the R-ER and nuclear envelope (in eukaryotes) - 30what is the structure of a Vacuole/ Vesical?STRUCTURE
Vacuoles and vesicles are membrane-bound fluid-filled spaces found in eukaryotic cells.
Vacuoles (large) - 31What is the function of Vacuoles?vacuoles (large)
FUNCTION
• Large vacuoles in plant cells maintain the water and salt balance in the cytoplasm and help keep the plant cell shape (tonicity) and may be used as a waste store.
•Contain ions, simple sugars and amino acids in a watery solution - 32what is the function and structure of a vesicle?Vesicles (small vacuoles)
FUNCTION
• Unlike plant cells other eukaryotic cells do not contain a large central vacuole.
Vacuoles in animal and fungal cells are smaller and more numerous.
STRUCTURE
Small vacuoles are called vesicles when transporting materials. They are composed of phospholipids to enable them to fuse with the cell membrane seamlessly, to expel their contents to the extracellular environment.
Additionally, they contain materials within the intracellular space for transportation. They bud off from the RER and Golgi. - 33what are the Lysosome?Lysosomes: a specialised vesicle.
Contains powerful digestive enzymes.
Often referred to as ‘SUICIDE SACS’
because they rid the cell of toxins - 34what is the cell wall?•Cell wall This structure of cellulose
and protein is only present in plant
cells. It provides structural support and protection. - 35what is the cell membrane?•Cell membrane This is the outer layer
of the cell made of phospholipids and
proteins which controls the movement
of materials into and out of the cell. - 36what is this?nucleas
- 37what is this?
- 38what is this?
- 39what is this?Ribsoms
- 40whats this?
- 41what is this?
- 42what is this?
- 43what is this?
- 44what is this?
- 45what is this?Red section: Rough ER
orange section: Smooth ER
- 46what is this?Chloroplast
- 47what is this?Mitichondria
- 48what is this?dark blue section: nucleolus
light blue section: nucleus
- 49what is this?dark section: nucleolus
light section: nucleus
- 50what is this?Mitochondria
- 51what is the cell membrane in simple words?Cell Membrane:
The selectively permeable nature of the cell membrane maintains relatively constant internal conditions by controlling molecular movement - 52what does protoplasm mean?A cell can be defined as a unit of protoplasm (living matter) that is separated from its external environment by a membrane.
- 53what is the structure of the cell membrane? Without the membrane the cell would lose its identity and be indistinguishable from its surroundings.
the membrane defines where a cell starts and ends.
The membrane is fundamental to BOTH regulating the flow of chemicals into and out of the cell as well as giving it structure!
The Cell membrane dictates what can and connot enter or the leave the cell. - 54what are the functions of a cell membrane?1. Separate the contents of the cell from the external environment.
2. Regulate the flow of substances into and out of the cell.
3. Molecular recognition: enable cells to ‘recognise’ each other.
4. Enable anchorage of the cytoskeleton. - 55definition of the cell membraneThe cell membrane is a flexible barrier that surrounds the cell, made of a phospholipid bilayer with embedded proteins. It controls the movement of substances in and out of the cell, maintaining homeostasis. The membrane is selectively permeable, allowing nutrients to enter, waste to exit, and preventing harmful substances from passing through. It also plays a role in cell communication, recognition, and adhesion, and contains cholesterol to maintain fluidity and stability.
- 56what is the structure of the phospholipids bi-layer?Structure of phospholipids:
• Phospholipids have a water attracting head (hydrophilic). Consist of a polar head
(hydrophilic) composed of a glycerol and a phosphate molecule
• Water repelling tails (hydrophobic). Consist of two non-polar tails (hydrophobic)
composed of fatty acid (hydrocarbon) chains
• Dispersed amongst the lipids are two types of protiens. - 57what is the arrangement of the phospholipid bi layer?Arrangement in membranes:
• Phospholipids spontaneously arrange into a bilayer
• The hydrophobic tail regions face inwards and are shielded from the surrounding
polar fluids, while the two hydrophilic head regions associate with the cytosolic and
extracellular fluids respectively - 58what is the properties of the phospholipid bi layer?Properties of the phospholipid bilayer:
• The bilayer is held together by weak hydrophobic interactions between the tails
• Hydrophilic/hydrophobic layers restrict the passage of many substances
• Individual phospholipids can move within the bilayer, allowing for membrane fluidity and flexibility
• This fluidity allows for the spontaneous breaking and reforming of membranes
(endocytosis / exocytosis - 59what is the difference between an active process and a passive process in the cell membrane?Active processes require energy (usually ATP) and move substances against their concentration gradient (e.g., active transport, endocytosis, exocytosis).
Passive processes do not require energy and move substances down their concentration gradient (e.g., diffusion, facilitated diffusion, osmosis). - 60what are the 3 passive processes?Simple diffusion
Osmosis
Facilitated Diffusion - 61what are the 3 active processes?Active Transport
Endocytosis
Exocytosis - 62what is simple diffusion ?Simple diffusion is the process by which small, nonpolar molecules (like oxygen, carbon dioxide, and lipids) move directly through the cell membrane from an area of high concentration to an area of low concentration, without the use of energy or assistance from transport proteins. This movement occurs naturally due to the random motion of molecules. Simple diffusion continues until equilibrium is reached, meaning the concentration of the molecules is the same on both sides of the membrane.
- 63what is osmosis?Osmosis is the movement of water molecules across a selectively permeable membrane from an area of low solute concentration to an area of high solute concentration. This process occurs to balance the concentration of solutes on both sides of the membrane. Osmosis does not require energy and is a type of passive transport.
Water moves through the membrane via specialized channels called aquaporins, though it can also pass directly through the lipid bilayer - 64What is facilitated diffusion?Facilitated diffusion is a passive transport process where molecules move across the cell membrane with the help of specific transport proteins, like channel or carrier proteins. It doesn't require energy and occurs along the concentration gradient (from high to low concentration). Examples include the movement of glucose or ions like potassium.
- 65what is active transport?Active transport is the movement of molecules across a cell membrane against their concentration gradient (from low to high concentration) using energy, typically in the form of ATP. Unlike passive transport, which doesn't require energy, active transport requires specific proteins called pumps to carry molecules across the membrane. An example is the sodium-potassium pump, which moves sodium ions out of the cell and potassium ions into the cell.
- 66what is Endocytosis?Endocytosis is the process where a cell takes in substances by engulfing them with its membrane, forming a vesicle. It requires energy and can involve phagocytosis (large particles), pinocytosis (fluid), or receptor-mediated endocytosis (specific molecules).
- 67what is Exocytosis?Exocytosis is the process where cells expel substances by vesicles fusing with the cell membrane, releasing their contents outside the cell. It requires energy (ATP) and is used to transport large molecules like hormones, neurotransmitters, or waste products out of the cell.
- 68why do cells divide?Cell division is the basis of:
Growth
Repair
Reproduction
• The ratio of cell membrane SA:V
ratio is a factor that limits cell size.
• When a cell reaches its OPTIMUM
size the NUCLEUS initiates cell
division. - 69why does the amount of DNA in a cell double before it is divided?Chromosomes and DNA:
Prokaryotes: DNA is in a single circular chromosome in the cytoplasm. Before cell division, the DNA is copied through binary fission so that both new cells have identical DNA.
Eukaryotes: DNA is in multiple linear chromosomes. Cell division is more complex and tightly controlled through the cell cycle. During division, DNA is copied through semi-conservative replication to ensure both daughter cells receive identical DNA - 70what are the cells that divide?Cells that divide are STEM CELLS.
- 71what happens when a Stem Cell divides?When Stem Cells divide one daughter cell
remains a stem cell the other
DIFFERENTIATES.
A differentiated cell has
become ‘SPECIALISED’ in structure and function
These cells tend not to divide or at least
divide at a greatly reduced rate.
Differentiated cells can’t revert back to
their former state. - 72Where is a cell that has been differentiated in the process of division?A cell that has differentiated is said to be
in G0. Its division apparatus is disabled and
if it is ever stimulated to divide again it
will occur very slowly. - 73what is the Cell cycle?The cell cycle has two main parts;
1. Growth and preparation (Interphase)
2. Cell Division (MITOSIS)
Cell division is split further into two stages
1. MITOSIS (Nuclear Division)
2. Cytokinesis (Cytoplasm Division)
Mitosis the division of the nucleus is divided into four stages
1. Prophase
2. Metaphase
3. Anaphase
4. Telophase
- 74what are the 4 stages in mitosis?1. Prophase
2. Metaphase
3. Anaphase
4. Telophase - 75What is Interphase?Cells spend most of their life cycle in Interphase.Interphase is the part of the cell cycle that occurs between divisions and is characterized by GROWTH & DEVELOPMENT.
• In the past biologists thought that Interphase was a ‘resting period’ because when viewed through a microscope during this phase the cell doesn’t appear to do anything. We now know that Interphase is the longest part of the cell cycle and the cell is very busy producing
materials for growth and synthesizing DNA in readiness for division.
• Interphase is divided into THREE parts:
1. G! or Gap 1: the first growth and
development period following division
2. S or Synthesis : the second stage
where the cell replicates the
chromosomes and commits to division
3. G2 or Gap 2 : the final growth stage, the
cell synthesizes organelles. - 76what is the process of Semi-conservative Replication?1. The two strands of the DNA helix are untwisted and then unzipped by the enzyme DNA Helicase (ie the bonds between the Complementary bases are broken.
2. Each DNA strand can then act as a template for the new strand of DNA.
3. Free deoxyribo-nucleotides produced in the cytoplasm migrate into the nucleus and bind to the exposed bases on the nucleotides of the Original DNA strands (annealed by Ligase).
4. The new nucleotides are then joined together to form a new DNA strand that is complementary to the original or Template strand.
5. The DNA molecules then re-twist into two separate DNA molecules
6) Thus two identical DNA molecules are produced each consisting of one old strand and one new strand.
7) This is why this replication is called Semi-Conservative - 77what is prophase?Prophase:
• chromatin shorten and condense to
form chromosomes
• the nuclear membrane disappears
• centrioles start to move to opposite
poles of the cell and spindle fibres
start to form - 78what is Metaphase?Metaphase:
• chromosomes line up on spindle
fibres across the equator of the cell
(one chromosome per spindle fibre). - 79what is Anaphase?Anaphase:
• the centromeres split moving sister
chromatids to opposite poles - 80what is Telephase?Telophase:
• daughter chromatids reach opposite
ends of the cell and nuclear
membranes reform
• cytokinesis occurs and the cell splits
into 2 identical daughter cells. - 81how do prokaryotic cells divide??Binary Fission
- 82what is Binary Fission?Bacteria reproduce by binary fission which
literally means “dividing in half”.
• The DNA in a bacteria replicates prior to cell division and then the plasma membrane and the cell wall grow inward to constrict the cell and divide it into two (cytokinesis).
• Each daughter cell is genetically identical to the parent cell.
• This process takes 20 minutes and thus
bacteria can multiply exponentially.
• If environmental conditions change and one bacteria dies, all are likely to die as they are identical unless there has been a mutation. Prokaryotic Cells Divide by Binary Fission - 83—
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- Biology FlashCards sobre cell flash cards , criado por izzy James em 18-02-2025.
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- izzy James · fev 2025
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