Biology AS Level UNIT 1


Flashcards on Biology AS Level UNIT 1, created by Valentin Andrei on 07/12/2014.
Valentin Andrei
Flashcards by Valentin Andrei, updated more than 1 year ago
Valentin Andrei
Created by Valentin Andrei about 9 years ago

Resource summary

Question Answer
Diffusion The net movement of particles from an area of high concentration to an area of lower concentration
Osmosis The diffusion of water molecules across a partially permeable membrane, from an area of high concentration to an area of lower concentration
Facilitated Diffusion Moves particles down a concentration gradient, from a higher to a lower concentration, with the help of carrier proteins and channel proteins
Active Transport Uses energy to move molecules and ion across cell membranes, against a concentration gradient involving carrier proteins
Endocytosis The process where a cell surrounds a substance with a section of its cell membrane that pinches off to form a vesicle containing the ingested substance
Exocytosis Vesicles with the substance pinches off from the sacs of the Golgi Apparatus, moving towards the cell membrane, then fusing with the cell membrane and releasing their contents outside
Describe Rapid Gas Exchange Alveoli- large surface area to volume ratio(speeds up the process) Alveolar Epithelium+Capillary Endothelium are 1 cell thick(short diff. pathway) Alveoli-good blood supply(maintains conc. gradient) breathing in-out(steep conc. gradient)
Structure of an Amino Acid molecule
Formation of a Peptide Bond Amino Acid are joined together by the removal of a water molecule (condensation)
How to break a Peptide Bond Can be broken off by adding water (hydrolysis)
Polymerisation Amino Acids can be joined together through a series of condensation reactions called ...
Primary Structure of Proteins The sequence AA in a polypeptide chain forms the primary structure of any protein. It determines its ultimate shape and hence its function. Alter its shape -> won't function as well, if at all
Secondary Structure of Proteins The polypeptide chain doesn't remain flat and straight. Hydrogen Bonds form between AAs in the chain. It makes it coil into a Alpha Helix or fold into a Beta Pleated Sheet.
Tertiary Structure of Proteins This 3-dimensional structure is held in place by chemical bonds (ionic, hydrogen and disulphide) between individual amino acids by hydrophobic interactions between R Groups.
Quaternary Structure of Proteins This structure arises from the combination of a number of different polypeptide chains and associated non-protein (prosthetic) groups into a large complex protein molecule.
Fibrous Proteins -Little or no Tertiary Structure; -Long parallel polyp. chains; -Insolubile in water, very tough; -Found in connective tissue, tendons, collagen, struct. of muscles and keratin;
Globular Proteins -Complex tertiary and smtms Q. structure; -Folded into spherical shapes; -Big protein therefore forms a colloid in water; -Antibodies, enzymes and some hormones
Enzymes Use your sheet
How a Mononucleotide is formed and its Structure -Deoxyribose (a 5-Carbon sugar) -A Phospate Group -An organic base (contains nitrogen) LINKED together by a condensation reaction
Formation of a Dinucleotide Formed after a condensation reaction between the deoxyribose sugar of one mono nucleotide and the phosphate group of another.
Formation of a Polynucleotide The continued linking of mono nucleotides by condensation reactions form a long chain known as ...
DNA Structure 2 long strand of polyn. twisted around each other to form a double helix, like a spiral case. The sugars and phosphates from the "backbone" of the molecule and are on the outside. The bases point inwards and are held together by hydrogen bonds.
Formation of a Double Helix 2 complementary DNA strands join together by Hydrogen bonding between bases. Each base can only join one specific partner by complementary pairing.
DNA Replication DNA unzips, one strand acting as a template for a new strand. Free floating mononuc. join each original template strand by complem. base pairing. The mononuc. on the new strand are joined together by DNA polymerase, then H bonds from between bases. Each DNA molecule contains 1 original strand and a new formed one
Describe Semi-Conservative DNA Replication bacteria grown - either in light or heavy nitrogen (bacteria produces - takes up N - integrates into DNA) 2, samples taken, spun in centrifuge - heavy N bacteria settled lower 3, heavy N bacteria grown light - sample taken then spun 4, IF IT WAS CONSERVATIVE - dna would separate 5, THEY FOUND - dna settled in the middle - mixture of heavy & light I.e SEMI CONSERVATIVE
What is a Gene? Is a sequence of bases that codes for the sequence of amino acids in a protein.
What is a triplet/codon? Each amino acid is coded for by a sequence of 3 bases called...
Transcription 1: DNA helicase breaks h-bonds - DNA unwinds on the SPECIFIC triplet code for a protein... 2: One strand acts as template - free RNA nucleotides line up on template, according to complementary base pairs (U replaces T)... 3: Condensation reaction > peptide bonds form between RNA making mRNA... 4: mRNA leaves through nuclear pore to ribosome for transcription. 5: DNA polymerase coils dna back up
Translation 1: mRNA attaches to ribosome 2: tRNA molecule w/ amino acids attaches > complimentary base pairing of anti-codons to codons 3: Amino acids joined by peptide bonds 4: tRNA moves away 5: attaching & moving until stop-codon reached *polypeptide (amino acid) chain moves away from ribosome
Structure of mRNA Phosphate, pentose sugar, complementary base (U replaces T)... SINGLE stranded It encodes a chemical blueprint of DNA for a protein product, later to be used in the ribosome, being formed in the nucleus
Describe how a molecule of mRNA is made during Transcription -DNA molecule "unzips" as H bonds between strands break -Free nucleotides line up along 1 strand of DNA- the antisense strand -The nucleotides follow the complementary base pairing pattern -RNA Polymerase, an enzyme, bonds the nucleotides together, forming phosphodiester bonds in a condensation reaction forming the mRNA strand
Describe tRNA structure Single folded polynucleotide strand binding site w/ specific amino acid each tRNA has the Anti-codon > binds to codon on mRNA -Mediates recognition of the codon and provides corresponding amino acids
The Genetic Code The way the DNA codes for proteins where each amino acid is coded for by a sequence of 3 bases called a triplet/codon in a gene
Template Strand Also called the antisense strand, is the one that serves as a model, after it was uncoiled, for the mRNA
Explain how errors in DNA replication can rise to mutations Mutations are changes in the base sequence of DNA caused by errors during DNA replication. The order of DNA bases in a gene determines the order of amino acids in a particular protein. If a mutation occurs in a gene, the primary structure of that protein it codes for could be altered, changing the final 3D shape of the protein making it not work properly.
Explain how Cystic Fibrosis results from one of a number of possible gene mutations If a mutation occurs in a gene, it can cause a genetic disorder like cystic fibrosis. The protein the gene codes for is important for mucus production
Allele A different version of a gene.
Genotype The alleles a person has, eg. BB or bb for eye colour
Phenotype The characteristics the alleles produce, e.g. brown eyes
Dominant An allele whose characteristics appears in the phenotype even when there's only one copy
Recessive An allele whose charact. only appears in the phenotype if 2 copies are present
Homozygote An organism that carries 2 copies of the same allele, eg. BB or bb
Heterozygote An organism that carries 2 different alleles, e.g. Bb
Carrier If a recessive allele can cause disease, a carrier is someone who has dominant and one recessive allele. They won't have the disease but they carry a copy of the allele for the disease
How does Cystic Fibrosis impairs the gaseous exchange, digestive and reproductive systems? -Mucus build up in the airways -The tube that connects the pancreas to the small intestine can be blocked with mucus, preventing digestive enzymes from reaching the small intestine. -The tubes connecting the testicles are blocked by mucus so no sperm and in women, thickened cervical mucus can prevent the sperm from reaching the egg
Describe Gene Therapy It involves altering the alleles inside cells to cure genetic disorders.
Differ the 2 types of Gene Therapy -Somatic Therapy: involves changing the alleles in body cells affected by a disorders. Doesn't affect one's sex cells->offsprings could inherit the disease -Germ line Therapy: involves changing the alleles in sex cells. Currently illegal
What is Genetic Screening? It involves analysing DNA to see if it contains alleles for genetic disorders. Has 3 main uses: identification of carriers, PGD and prenatal testing
Advantages and Disadvantages of Identification of Carriers ADV: -Couples can be tested before having children to determine the chances of any future child having the disorder. -Allows people to decide whether to have children or carry out Prenatal Testing Disadv: -The result may cause emotional stress. -The test aren't always 100% accurate. -Other genetic abnormalities can be found leading to further stress. -Results could be used by employers or life insurance companies- genetic discrimination
Advantages and Disadvantages of Preimplantation Genetic Diagnosis (PGD) ADV: -Reduces the chance of having a baby with a genetic disorder. -Performed before implantation, avoids the issue of abortion that could be raised by prenatal testing DISADV: -It can be used to find out other charact, raising the concern that embryos might be selected for other charact. -False results could provide incorrect info
Advantages and Disadvantages of Prenatal Testing ADV: -Allows parents to make informed decisions. If the test is pos, the parents decide whether to have the child or an abortion. This also provides info to prepare in advance for the baby's disorder DISADV: -It slightly increases the rate of miscarriage by 1% -False results could provide incorrect info -Some people consider it unethical to abort a fetus because it had a genetic disorder
Define Monosaccharides and give an example Are also called Carbohydrates, eg. Glucose is a M. with 6 carbon atoms in each molecule
Define Disaccharides and give examples The result of 2 Monosaccharides that are joined together by a Glycosidic Bond through a Condensation Reaction. Eg Maltose, Lactose and Glucose
Define Polysaccharides and give examples A P. is formed when more than 2 monosaccharides join together. Eg Amylose, Amylopectin and Glycogen
Name 2 different types of Polysaccharides that form Starch and detail their structure Amylose: unbranched chain of glucose joined together with 1-4 Glycosidic Bond. The angles of the G.B. give it a coiled structure that makes it compact, good for storage Amylopectin: branched chain of glucose that contains 1-4 and 1-6 G.B. Its side branches allow enzymes to reach the G.B. more easily-> glucose released quickly
Name the main energy storage material in animals and detail its structure Glycogen: 1-4 and 1-6 G.B. and has loads of branches off it which means enzymes reach the G.B. more easily-> glucose released quickly. Compact molecule-> good for storage Insolubile in water Large molecule-> can store lots of energy
Describe MALTOSE fully 1-4 G.B. and alpha-glucose
Describe LACTOSE fully beta-glucose and Galactose with 1-4 G.B.
Describe SUCROSE fully alpha-glucose and Fructose with 1-2 G.B.
Describe AMYLOSE fully Alpha-glucose and 1-4 G.B.-> angles-> coiled structur-> compact so good for storage
Describe AMYLOPECTIN fully alpha-glucose and 1-4 and 1-6 G.B with LOTS of branches
Describe GLYCOGEN fully alpha-glucose with 1-4 and 1-6 G.B. with LOTS and LOTS of branches-> glucose released quickly as enzymes reach the bonds fasterCompact molecule-> good for storage Insolubile in water Large molecule-> can store lots of energy
WHEN and WHERE does a Glycosidic Bond occur? How do you break them off? Carbohydrates: After a condensation reaction between 2 monosaccharides. By hydrolysis.
Describe the structure of a Triglyceride
What are the long tails in Triglycerides made of and what's their main property? Hydrocarbons. The tails are hydrophobic making lipids insoluble in water.
WHEN and WHERE does an Ester Bond occur? How do you break them off? They are the result of a condensation reaction between Triglycerides (Lipids) and are broken off by hydrolysis
Define a SATURATED Lipid Don't have any Double Bonds between Carbon atoms in their hydrocarbon tail. They're saturated with HYDROGEN.
Define an UNSATURATED lipid They have Double Bonds between Carbon (if multiple-polyunsaturated) atoms-> are not saturated with Hydrogens. The Double Bonds cause the chain to kink.
WHEN and WHERE does a Peptide Bond occur? How do you break them off? Result of a condensation reaction between 2 amino acids (Proteins). Broken off by hydrolysis.
Define the Mass Transport Systems? Systems used to carry raw materials from specialised exchange organs (lungs or digestive system) to the body cells and to remove metabolic waste (carbon dioxide)
Why do multicellular organisms need mass transport systems? In mammals, the mass transport system is the circulatory system where blood is used to transport substances around the body (oxygen and glucose)
Features of ARTERIES -Carry blood from the heart to the rest of the body -Thick-walled, muscular and have elastic tissue to cope with the high pressure caused by the heartbeat -The inner endothelium is folded, allowing the artery to expand to cope with high pressure
Features of Veins -Take blood back to the heart -Wider than arteries -Little elastic or muscle tissue -Contain valves to stop the blood from flowing backwards -Blood flow helped by the contraction of muscles sourrounding them
What is a eukaryotic cell? A complex large cell with a nucleus, that containing membrane bound organelles e.g. animal and plant cells
What is a prokaryotic cell? What is a prokaryotic cell? A simple small cell with no nucleus containing no membrane bound organelles e.g. bacteria
Nucleus Large organelles surrounded by a nuclear envelope containing chromatin and a nucleolus. Chromatin: made from proteins and DNA Nucleolus makes ribosomes
What are Lysosomes? Round organelle surrounded by a membrane, containing digestive enzymes used to digest invading cells or break down worn out components of the cell
What are Vesicles? Small fluid filled sac in the cytoplasm that transports substances in and out of the cell; Some formed by the Golgi A. or E.R - or formed at the surface
What are Ribosomes? Small organelle that floats free in the cytoplasm or attached to the R.E.R; The site where proteins are made
What is Rough Endoplasmatic Reticulum? A system of membranes arranged in stacs enclosing a fluid filled space covered in ribosomes; Folds and processes proteins that have been made at the ribosomes
What is Smooth Endoplasmatic Reticulum? A system of membranes arranged in stacs enclosing a fluid filled space; Synthesise and process lipids
What is Golgi Apparatus? A group of fluid filled flattened sacs that have vesicles attached to them; Makes and packages new lipids, proteins and lysosomes
What is Centriole? Hollow cylinders containing microtubules; Helps with the separation of chromosomes during cell division
What is a Mitochondrion? Oval-shaped organelle with a double membrane, the inner one folded -> cristae. Inside is the matrx -> enzymes for respiration; The site of aerobic respiration where ATP is made
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