Year 11 Unit 1 Exam revision Flashcards

Question

Ribosome function

Answer 1

The site for protein synthesis in the cell

Answer 2

Controlling the correct number of chromosomes

Answer 3

The digestive system. It contains digestive enzymes, breaks down cell waste and toxins, and acts like a garbage disposal.

Answer 4

A cell organelle that helps process and package proteins and lipid molecules

Answer 5

Helps excrete waste products or store extra liquids

Answer 6

They are the site of photosynthesis

Answer 7

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

Answer 8

Network of proteins that start at the nucleus and reach the plasma membrane. It maintains shape and transports vesicles around the cell.

Answer 9

Glucose + oxygen —> carbon dioxide + water + energy

Answer 10

Mitochondria are the sites of aerophobic cellular respiration, a necessary process for all organisms to break down sugars energy. The space inside the inner membrane is known as the mitochondrial matrix and the folds of the inner membrane are known as the cristae. Cellular respiration is the cell’s primary method of producing energy.

Answer 11

They are the sites of photosynthesis in organisms that use sunlight to create sugars. Grana is found within, made of a stack of flattened sacs known as thylakoids + fluid substances known as stroma. They also help plants undergo photosynthesis

Answer 12

Photosynthesis is the process in which light is used as energy from the sun, carbon dioxide, and water to produce glucose and oxygen. It takes place within the thylakoid membrane and contains a green pigment known as chlorophyll which absorbs light to energize the reaction.

Answer 13

Carbon dioxide + water → sunlight → glucose + oxygen

Answer 14

Cells need a high SA:V ratio because they need to transport lots of substances across their border tend to be small and & elongated. For instance, in the small intestine, which is responsible for absorbing nutrients, cells lining the intestine arrange into ‘finger-like’ shapes called villi

Answer 15

The plasma membrane is like the "skin" of a cell. It surrounds the cell and keeps all the cell's parts inside while also protecting it from the outside environment. The boundary of all living cells controls entry of dissolved substances into and out of the cell

Answer 16

1. Phospholipids 2. Proteins 3. Carbohydrates 4. Cholesterol

Answer 17

**Hydrophobic : ** * H2O fearing/repelling * Non-polar molecules * Molecules where the charge is equal * Can easily cross the plasma membrane **Hydrophilic ** * H2O loving * Polar molecules * Molecules where the charge is shared unequally * May need assistance to cross the membrane * E.g. protein channel

Answer 18

Double layer (bilayer) of phospholipids -2 fatty acid chains (tails) // Non-polar = hydrophobic -1 phosphate containing group (head) // Polar = hydrophilic

Answer 19

There are two types of proteins **1. Integral proteins: ** * Permanent part of the membrane * Transmembrane – integral proteins that span front he inside to the outside of the bilayer * E.g. Protein channels and glycoproteins **2. Peripheral proteins** * Temporary proteins that attach to the outside of the membrane * E.g. Cytochrome C

Answer 20

* Aka the sugars of the plasma membrane * Hint: Look for the word “gly” * Glycoproteins are proteins that have carbohydrate molecules covalently attached to certain amino acids **1. Glycoproteins ** * Carbohydrates attached to an integral protein * Generally antigens/self markers (self markers to let the body know that it’s meant to be there so that the body does not eliminate it) **2. Glycolipids ** * Carbohydrates attached to a lipid * Involved in tissue identification * Glycolipids are lipids with carbohydrate molecules attached. They consist of a hydrophobic lipid tail and one or more hydrophilic carbohydrate (sugar) groups. These carbohydrate groups are typically attached to the lipid molecule through a glycosidic bond

Answer 21

* Embedded in between trh4 fatty acid tails * Aid in structure (warm) and fluidity (cold) * Cholesterol is a lipid classified as a sterol, featuring four linked hydrocarbon rings, a hydrocarbon tail, and a hydroxyl group. It is an essential component of animal cell membranes and serves several important functions

Answer 22

The fluid mosaic model is so called because like a mosaic it is makeup of different types of molecules (lipids and proteins) that are side by side, and also because it is fluid that flows (think of it like a soap bubble)

Answer 23

* Integral proteins extend into the hydrophobic space in the membrane * Transmembrane proteins are integral proteins that extend from one side of the membrane to the other * They help move substances in and out of the cell, receive signals from outside, and help cells stick to each other. They are important for many functions that keep cells working properly *

Answer 24

* Peripheral proteins interact only interact with the hydrophilic head of phospholipids * They often help with signalling, shape, and structure of the cell, and can assist with various cellular functions by interacting with other proteins and molecules

Answer 25

When molecules move from an area of high concentration to an area of low concentration (down their concentration gradient) This process requires no enenrgy Only, small nonpolar molecules can freely diffuse through the phospholipid bilayer. Large and hydrophilic molecules (ions, amino acids, proteins, glucose, or nucleic acids) will simply bounce off the membrane and be unable to diffuse. Leading to a higher concentration of molecules on one side.

Answer 26

Facilitated diffuion is for larger molecules or too charged (ie. glucose and ions) to freely cross the membrane can use a membrane protein, known as a protein channel, to move down their concentration gradient into our out-of-cell. It is a type of passive movement of molecules down their concentration gradient through membrane-bound proteins. Allows large/or polar molecules to move between intra/extracellular environments through protein channels OR carrier proteins. * **Protein channels** are pores/holes in the membrane that let specific substances through * **Carrier proteins** bind to substances that are being transported to undergo conformational change, pushing substances down the concentration gradient through the other side of the membrane. Returning to its original shape once the molecule is transported.

Answer 27

Osmosis is the diffusion of water from an area of low solute concentration to an area of high solute concentration across the selectively permeable membrane. * Water molecules can move through the phospholipid bilayer despite being hydrophilic due to how small they are, water movement can increase due to protein channels known as aquaporins. * Many solutes can’t cross the membrane due to its selectively permeable nature, except water

Answer 28

Solutions have comparatively low solute concentrations, water moves from a hypotonic solution in adjacent areas with a higher solute concentration (think of the PO in hyPO-tonic as "pop"-- because the cell will swell up and possible explode)

Answer 29

In solutions with higher solute concentrations, water moves into a hypertonic solution from adjacent areas with lower solute concentrations

Answer 30

The solution has equal solute concentrations, and there is a lack of net movement of water. There is still movement of water into and out of a compartment, though the rate of water moving is equal to the rate of water moving out, making the net movement zero.

Answer 31

The tonicity of solutions will impact the cell size. If cytosol in plant cells were hypertonic compared to extracellular fluid, water then moves into the cell, causing swelling and becoming turgid. The cell remains turgid (rather than burst) due to the cell wall. When water moves out of the plant cell, occurring when the cell is hypotonic compared to the extracellular fluid, the cell begins to shrink and becomes plasmolyzed. Due to animal cells lacking cell walls, when they are placed into hypotonic solutions their volume will increase becoming, lyse. To regulate tonicity and osmosis is significant to preventing a plant from wilting. + eg. If put onto a hospital drip you are given a saline solution to remain hydrated (none pure water) The saline solution is isotonic in cells, this ensures cells in the blood do not shrivel nor lyse.

Answer 32

* Nonpolar/hydrophobic, small molecules (oxygen and carbon dioxide). * Down concentration gradient * No protein requried * No energy required

Answer 33

* Polar/hydrophilic, large molecules (ions, amino acids, glucose). * Down concentration gradient * Proteins are required * Energy is required

Answer 34

* Water * From hypotonic to a hypertonic solution * Proteins are sometimes required (aquapornis) * No energy requried

Answer 35

* Transporting substances across the membrane involves using protein pumps to move molecules against their concentration gradient. There are two types of active transport; Protein-mediated active transport & Bulk transport * Active transport is the movement of molecules across the membrane that DOES require energy * Active transport ios substances across membranes involves using protein pumps to move molecules against their concentration gradient *

Answer 36

1. Protein-mediated active transport (this is also known as just active transport) 2. Bulk transport

Answer 37

Protein-mediated active transport uses energy to move substances across the cell membrane from lower to higher concentration. These proteins act like pumps, directing substances where they are needed Energy usually in the form of adenosine triphosphate (ATP) this is the main source of chemical energy within cells and powers almost all of the process within a cell

Answer 38

* Bulk transport is a process where cells move large amounts of substances, like proteins or particles, into or out of the cell. This can happen in two main ways: by engulfing them (endocytosis) or by releasing them (exocytosis). It helps cells take in nutrients and get rid of waste * When extremely large substance need to be moved across a cell membrane, bulk transport is used * This active process uses ATP to move vesicles around the cytoplasm and to change the shape of the cell

Answer 39

* (think of the word “endo” as “enter”) * Endocytosis is the bulk transport of material into the cell, and it can be split into two processes: Phagocytosis & pinocytosis **Phagocytosis:** * Phagocytosis is a process where a cell surrounds and engulfs large particles with the plasma membrane to take them inside. It's like the cell eating the particles to break them down and use or dispose of them. * This is important for cleaning up and defending the body against infections * Basically engulfs solid particles / eating **Pinocytosis:** * Pinocytosis is a process where a cell takes in small droplets of liquid from its surroundings. It's like the cell drinking the liquid to absorb nutrients and other important substances dissolved in it. * Basically takes in droplets of liquid / drinking

Answer 40

* (think of the word “exo” as “exit”) * Exocytosis is a process in which a cell releases substances stored in vesicles (small sacs) into the external environment. It's like the cell packaging and sending out molecules or waste materials through its membrane to communicate with other cells or remove waste from the body. * It is the reverse of endocytosis

Answer 41

ATP, or adenosine triphosphate, is like a cell's energy currency. It stores and transfers energy within cells for various functions such as muscle contraction, protein synthesis, and powering active transport processes. In simple terms, it's often called the "energy molecule" of cells. ATP is made by cells converting the energy stored in food molecules into a form that they can readily use for various functions

Answer 42

A + T C + G

Answer 43

Cell replication also known as cell reproduction or cell division, refers to the process by which a cell duplicates its contents and divides into two daughter cells. This fundamental process is essential for growth, development, and maintenance of organisms, as well as for replacing damaged or old cells.

Answer 44

* Binary fission is a type of asexual reproduction commonly found in prokaryotes such as bacteria, as well as in some single-celled eukaryotes like amoebas. In this process, a single organism divides into two parts, each of which can grow to the size of the original organism * This process typically occurs in prokaryotes like bacteria and archaea * Produces two genetically identical copies of a cell * E.g. 2 → 4 → 8 → 16 → etc

Answer 45

This process happens very fast, allowing organisms to grow, repair damaged tissues, or reproduce quickly. For example, bacteria can divide rapidly to produce many new cells in a short time, which helps them spread and survive.

Answer 46

1. DNA replication 2. Eliongation 3. Septum formation 4. C ell division

Answer 47

The process begins with the replication of the organism's DNA. In prokaryotes, DNA is typically a single circular chromosome located in the nucleoid region. The DNA molecule unwinds and duplicates itself, forming two identical copies attached at a point called the origin of replication.

Answer 48

* As the DNA replication proceeds, the cell elongates. This elongation is important because it prepares the cell to split into two daughter cells * Once the chromosomes have attached to the cell membrane, the cell grows in length, as new cell wall material is laid down

Answer 49

* Septum (or partition) begins to form at the centre of the cell. This septum is made up of proteins and other materials that constrict the cell from the inside, dividing it into two compartments * We can tell when there are little gaps at the top and bottom of the cell

Answer 50

* Cell wall degrading enzymes digest the centre of the cell wall, dividing the septum, resulting in two separate cells, each genetically identical to the other. * Finally, the two daughter cells fully separate. Each daughter cell is now an individual organism identical to the original cell in terms of genetic material and cellular composition.

Answer 51

* Plasmids carry a small number of non-essential genes and are copied independently of the chromosome inside the cell. * They can be transferred to other prokaryotes in a population, sometimes spreading genes that are beneficial to survival. * Think of it as a way where prokaryotes can save their population from being destroyed because they had persevered through some extra genes

Answer 52

1. Interphase 2. Mitosis 3. Cytokinesis

Answer 53

* First and longest of all phases. * Synthesis the necessary DNA, proteins, and organelles required for growth. * DNA can exist as long as chromatin threads instead of discrete chromosomes (Chromosomes that have been unwound and loosely packaged) * * Three sub-stages of interphase known as G1 phase, S phase, and the G2 phase * If further cell replication isn't required, the cell can exit the cycle in G1 to enter G0 (resting phase)

Answer 54

* Increasing the volume of its cytosol * Synthesising proteins for DNA replication * Replicating its organelles * [Cell will now proceed to S phase or exit to G0 with no further replication].

Answer 55

For no further replication, the cell will go into G0 to rest (tf get up). Cells in this phase are either quiescent or terminally differentiated. Quiescent are dormant and have the ability to re-enter the cell cycle, terminally differentiated cells remain in G0.

Answer 56

* Cells will replicate their DNA turning one chromosome into two genetically identical sister chromatids * A centromere holds Sister chromatids, the pair is called a single chromosome * During mitosis when sister chromatids separate, each chromatin is considered a single chromosome

Answer 57

* The final stage of interphase where cells continue to grow and prepare for mitosis * Similar to G1 * Increases the volume of cytosol (fluid within the cytoplasm) * Synthesising proteins to prep for mitosis

Answer 58

* Mitosis is the second stage of the cycle and involves the separation of newly replicated chromosomes to two new nuclei * Mitosis has four sub-stages known as prophase, metaphase, anaphase, and telophase.

Answer 59

I) Interphase = I P) Prophase = Pray M) Metaphase = More A) Anaphase = At T) Telophase = The C) Cytokinesis = Church

Answer 60

Condensation of chromatin around histones to distinct chromosomes. Simultaneously, centrioles migrate to opposite ends of the cell, spindle fibres will form. The nuclear membrane breaks down while the nucleolus disappears.

Answer 61

Spindle fibres fully form, attaching to the centromere of each chromosome. Allowing spindle fibres to guide chromosomes to the equator of the cell to line up.

Answer 62

Spindle fibres contract, splitting centromeres and pulling sister chromatids to the opposite end of the cell.

Answer 63

Chromosomes pack together at either end of the cell, new nuclear membrane forms, producing two g/identical nuclei. Spindles will disintegrate, and chromosomes decondense. (Reverse prophase)

Answer 64

After mitosis, cytokinesis commences. The cytoplasm divides and organelles evenly distribute themselves before separating into two daughter cells.

Answer 65

The cycle has checkpoints where it will inspect itself for errors, this happens during the end of G1 and G2. If an error is found, the cell can pause and repair although if the damage is irreversible, the cell can undergo programmed cell death (apoptosis) * G1 verifies the cell has grown to the correct size, synthesises enough protein for DNA replication, checks DNA for damage during mitosis and growth, and checks for enough nutrients and oxygen. * G2 ensures the DNA has replicated correctly during S phase, and that the cell has enough resources for mitosis * Metaphase the cell checks the formation of spindle fibres. The chromosomes are lined in the correct location to proceed into anaphase.

Answer 66

Apoptosis is a process in biology where cells self-destruct in a controlled and organised way. This "cell death" is a natural part of development and health, helping to remove old, damaged, or unneeded cells. It's like the body’s way of cleaning up and making room for new cells. Cells, like all living things, cannot live forever.

Answer 67

**1) Initiation of Apoptosis** * Apoptosis can be triggered by internal signals (e.g., cellular stress, DNA damage) or external signals (e.g., death receptor activation by ligands) **2) Activation of Caspases** * Enzymes shred the dying cells DNA and the nucleus is dismantled and condensed * Initiator caspases (the enzymes, such as caspase-8 or caspase-9) become activated in response to apoptotic signals **3) Execution Phase** * Activated caspases cleave various cellular proteins, resulting in characteristic morphological changes within the dying cell **4) Formation and Clearance of Apoptotic Bodies** * The apoptotic cell undergoes further changes, including membrane blebbing and fragmentation into smaller apoptotic bodies (Apoptotic bodies, which are membrane-bound vesicles containing cellular debris from the apoptotic cell)

Answer 68

Apoptosis is important because it helps keep the body healthy by getting rid of cells that are no longer needed or are damaged. This process prevents potential problems, such as the development of cancer from damaged cells, and ensures proper development and functioning of tissues and organs. It's like the body's way of taking out the trash to maintain a clean and healthy environment.

Answer 69

**Developmental processes : *** Apoptosis plays a crucial role during embryonic development and tissue remodelling * It helps sculpt and shape developing organs and tissues by eliminating unwanted, excess, or improperly positioned cells * For example, apoptosis is responsible for the formation of fingers and toes during human foetal development, where cells between the digits undergo programmed cell death to separate them

Answer 70

**Maining tissue homeostasis: ** Apoptosis is important for homeostasis, which is the body's way of maintaining a stable and healthy internal environment. By removing old, damaged, or unnecessary cells, apoptosis helps keep the right balance of cells in the body. This prevents problems like uncontrolled cell growth, which can lead to tumours, and ensures that tissues and organs function properly.

Answer 71

**Elimination of virally infected cells :** Apoptosis is one of the mechanisms the body uses to eliminate cells infected with viruses. By destroying infected cells, apoptosis limits viral replication and spread within the body, aiding in the immune response against viral infections

Answer 72

Cancer is a term used to describe a group of diseases characterised by the uncontrolled growth and spread of abnormal cells. These cells have lost the ability to regulate their growth and division like normal cells, leading to the formation of tumours or abnormal masses of tissue. Cancerous cells can invade nearby tissues and organs an can also spread to other parts of the body through the bloodstream or lymphatic system, a process known as metastasis

Answer 73

Cells become cancerous when they undergo changes (mutations) in their DNA that cause them to grow and divide uncontrollably. Normally, cells have mechanisms to repair damage or to self-destruct (apoptosis) if the damage is too severe;. However if these mechanisms fail, the damaged cells can continue to multiply,forming a mass of cells called a tumour.

Answer 74

*** Genetic Factors :** Inherited mutations can make some people more prone to cancer. *** Environmental Factors :** Exposure to harmful substances like tobacco smoke, radiation, and certain chemicals can damage DNA. *** Lifestyle Factors :** Poor diet, lack of exercise, and other lifestyle choices can increase cancer risk. *** Infections :** Some viruses and bacteria can cause changes in cells that lead to cancer.

Answer 75

**1. Benign Tumours** * Benign tumours are abnormal growths of cells that are noncancerous and typically do not invade nearby tissues or spread to other parts of the body. They are essentially localised masses of cells that grow slowly are usually surrounded by a fibrous capsule **2. Malignant tumours :** * Cancerous cells fall under the category of malignant tumours * It is when abnormal cells invade nearby tissues and tumours cells can migrate to other parts of the body

Answer 76

**Uncontrolled cell growth :** * Cancer cells divide and proliferate continuously without responding to the signals that normally regulate cell growth and division * This leads to the formation of tumours and abnormal tissue growth **Metastasis :** * Cancer cells have the ability to detach from the primary tumour, enter the bloodstream or lymphatic system and invade/establish secondary tumours (metastases) in distant organs or tissues * This is a hallmark feature of malignant cancer **Loss of apoptosis :** * Cancer cells often evade apoptosis, a natural process of programmed cell death that eliminates abnormal or damaged cells * The purpose of apoptosis is to eliminate cells that contain potential dangerous mutations, if a cells apoptosis function is not working properly, the cell can grow and divide uncontrollably and ultimately create a tumour * This allows cancer cells to survive ab d proliferate uncontrollably **Increase cell survival :** * Due mutations in the regulation of the cell cycle, apoptosis no longer functions correctly in tumour cells * Tumour cells are also capable of replicative immortality, which theoretically allows them to divide forever, enhancing their survival

Answer 77

Stem cells are undifferentiated cells that can differentiate into specialized cells with a particular function.

Answer 78

Stem cell measures its capacity to differentiate into different cell types. Stem cells are created equal. They have varying capabilities, with some stem cells being able to change into any cell type. Based on relative capabilities stem cells can be categorised according to their relative potency.

Year 11 Unit 1 Exam revision Flashcards

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