Cells and DNA flashcards

Description

Edexcel Unit 2 Biology flashcards
Peter  Hoskins
Flashcards by Peter Hoskins, updated more than 1 year ago
Peter  Hoskins
Created by Peter Hoskins almost 9 years ago
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Resource summary

Question Answer
Cell membrane Selectively permeable - controls what enters and leaves a cell
Nucleus Control centre of the cell - contains DNA organised as chromosomes
Cytoplasm Where all the chemical reactions occur inside a cell
Mitochondria Structures in a cell which carry out respiration and release energy
Ribosome Where protein synthesis occurs inside a cell
Chloroplast Found in plant cells - carry out photosynthesis
Large cell vacuole Found in plant cells - contain cell sap and control water movement in and out of the cell
Cell wall Found in plant cells - made of cellulose - provide strength
Chromosomes Made of DNA - genes are found along their length
Amino acids The building blocks of protein
Transcription (HIGHER ONLY) When a copy is made of a DNA strand in the form of mRNA (HIGHER ONLY)
Translation (HIGHER ONLY) When mRNA is used to order tRNA molecules in order to sequence amino acids to make a specific polypeptide (HIGHER ONLY)
Double helix The shape of a DNA molecule - a 'twisted' ladder
Codon (HIGHER ONLY) A triplet of bases - each of which codes for a specific amino acid (HIGHER ONLY)
Base pairs The 'letters; in the DNA alphabet - cytosine (C) , guanine (G) , adenine (A) and thymine (T)
Mitosis Cell division for growth
Meiosis Cell division to produce sex cells (for sexual reproduction)
Diffusion Movement of molecules from a high to a low concentration
Osmosis Movement of water molecules through a semi-permeable membrane - from an area of high water concentration to an area of low water concentration
Diploid Chromosomes existing as pairs in a cell e.g. in humans the number is 46 (23 pairs) of chromosomes
Haploid The situation where chromosomes exist a single chromosomes in a cell e.g in humans there are 23 single chromosomes in egg and sperm cells
Enzyme A biological catalyst made from protein
Substrate The molecule an enzyme 'works on' - catalyses
Active site The part of an enzyme which combines with its' substrate - if its' shape is altered the enzyme will no longer work
Denatured When the shape of an enzyme is changed (e.g. by heat or the wrong pH) so its' active site no longer works to catalyse a reaction
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