biology
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- Created by: Eloise
- Created on: 30-05-14 12:52
Why do plants need water?
Photosynthesis, maintain structural rigidity, transport minerals, regulate temperature.
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Why do plants need magnesium ions?
Production of chlorophyll-pigment needed for photosynthesis
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Why do plants need nitrate ions?
Production of DNA, proteins (enzymes), chlorophyll, seeds, fruit and plant groeth
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Why do plants need calcium ions?
for growth, important component in cell walls
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What are the two cell types?
Prokaryote and Eukaryote
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Explain prokaryote
Simple, small, no nucleus or other membrane-bound organelles, rigid and strong cell wall- fully permeable
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Example of prokaryote
Bacteria; E.coli
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Example of eukaryote
Plant, animal, fungal cells
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What does the cell surface (plasma) membrane in prokaryotes do?
Partially permeable, controls movement of substances between the cell and its environment. Folded to give a large surface area where enzymes involved in reactions such as aerobic respiration are situated
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What are flagella used for?
Movement
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What is DNA in a prokaryote like?
Long, double helix forming a circular molecule, not contained in the nucleus
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What happens in ribosomes in prokaryotic cells?
Polypeptides and proteins are formed, following the code on the DNA molecule. Smaller than in eukaryotic
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What is mitosis and when does it take place?
Nuclear division-whenever growth and replacement of cells is taking place, and during asexual reproduction.
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What does mitosis produce?
New cells which contain exactly the same genes, with exactly the same base sequences as the parent cell
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What does mitosis involve?
Exact and equal division of chromosomes so that each daughter cell has exactly the same number and type of chromosomes as the parent cell
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What does the term diploid mean?
2 copies of each type of chromosome in their cells- humans have 2 copies of chromosome
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WHat is the haploid chromosome number?
Number of chromosomes in a single set
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What is cell differentiation?
Cells differentiate into different types depending on their position in the organism.
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What is asexual reproduction?
Production of new organisms from a single parent by processes which do not involve gametes or fertilisation. Often occurs in plants.
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Summary of prokaryotic cells
Bacteria; doesn't contain membrane-bound organelles; smaller ribosomes; circular DNA with no histones; DNA free in cytoplasm; no nucleus
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Summary of eukaryotic cells
Plants, animals and fungi; contains membrane-bound organelles; larger ribosomes; linear DNA with histones; Nucleus, containing DNA, bounded by nuclear envelope
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What happens during interphase?
The cell grows and DNA replication takes place
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What happens during cytokinesis?
The cytoplasm divides to form two genetically identical cells
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What are the four stages of mitosis?
Prophase, metaphase, anaphase, telophase
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What happens during prophase?
Chromosomes condense. Each chromosome is a double structure made from 2 genetically identical chromatids
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WHat happens during metaphase?
Nuclear membrane has gone, microtubules (spindle fibres) attach to the centromeres of each chromosome and pull on them and so arranging them along the equator of the cell
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What happens during anaphase?
Chromatids are pulled apart by the microtubules and move to opposite poles
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Hat happens during telophase?W
Chromosomes become less and less visible as they decondense (become longer and thinner)
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What do all eukaryotic cells have?
A double membrane (nuclear envelope) which surrounds an area containing DNA
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Two types of eukaryotic cells
Plant and animal cells
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What is a nucleus?
Membrane-bound region of the cell which contains the DNA
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WHat are chromosomes?
Each DNA molecule with its histones is a chromosome. When the cell is not dividing, chromosomes are not visible as threads but form dark and light areas- chromatin. When cells begin to divide, chromosomes curl up to form shorter, thicker structures.
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What is a nuclear envelope?
Double membrane which surrounds a nucleus, keeps DNA away from other activities going on in the cell, pores in the envelope allow mRNA to pass out into the cytoplasm
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What is a nucleolus?
Found in the nucleus- the darkly-staining area. WHere ribosomal RNA is being made by transcription from DNA
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What is the rough endoplasmic reticulum?
Network of membranes running through the cytoplasm, forming interconnecting compartments- cisternae. Rough as ribosomes are attached to the outer surfaces of the membranes. Proteins are made on these ribosomes.
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WHat happens to some of the proteins in RER?
Some pass into the cisternae which can break up into small vesicles and transport the proteins to other parts of the cell e.g. Golgi apparatus
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What is the smooth endoplasmic reticulum?
Similar structure to RER but no ribosomes. Site of synthesis of cholesterol and steroid hormones/
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What is the Golgi Apparatus?
Stack of curved cisternae where proteins made on the RER are package and modified ready for export from the cell. Vesicles move from the RER and become part of the face of the Golgi Apparatus. Inside the proteins may have carbohydrates added to them.
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What happens in the Golgi Apparatus after the proteins have carbs added forming glycoproteins?
Vesicles containing modified proteins break away form face of Golgi Apparatus and move towards plasma membrane. They fuse with the membrane by exocytosis so their contents are outside of the cell.
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What are lysosomes?
Vesicles which break away from the Golgi Apparatus. They can break down substances brought into the cell by phagocytosis or unwanted organelles inside the cell. Lysosome membrane fuses with organelle membrane releasing its enzymes onto it.
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Where are lysosomes found?
In animal cells, not in plant cells
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WHat are ribosomes?
Small structures made of rRNA and protein. Provide a site for the synthesis of proteins. If many work together they are polyribosome.
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WHat are mitochindria?
Sites of aerobic respiration, oxygen is used to release energy from organic molecules and make ATP. Double membrane, inner folded to form cristae providing a large surface area for respiration to take place. Contain own DNA and ribsomes- make protein
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What are chloroplasts?
Double membrane, only found in certain types of plant cells; sites of photosynthesis; contain membranes called lamellae which are folded to form sacs called thylakoids which stack together to form grana,
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Where are chlorophyll molecules embedded?
In the lamellae; chloroplasts often contain starch grains and contain their own DNA and ribosome.
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What are microtubules?
Tiny, hollow cylinders, found throughout the cytoplasm; made of the protein tubulin; help other organelles move within the cell. Spindle fibres are microtubules
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What are centrioles?
Animal cells contain 2 centrioles usually positioned outside the nuclear envelope; ie at right angles to each other; divide just before cell division and help to produce and organise microtubules which form spindle fibres
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What has a cellulose cell wall?
Plant cells; tough and protective, surrounding all of the cell outside the plasma membrane; made of fibres of cellulose embedded in a matrix of pectin and other materials; composite structure resistant to extension or compression
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WHat are cell membranes?
Whole cell is surrounded by plasma membrane (cell surface membrane); all of these ahve a similar structure; all control what passes through and are an attachment site for enzymes and other molecules.
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Other cards in this set
Card 2
Front
Why do plants need magnesium ions?
Back
Production of chlorophyll-pigment needed for photosynthesis
Card 3
Front
Why do plants need nitrate ions?
Back
Card 4
Front
Why do plants need calcium ions?
Back
Card 5
Front
What are the two cell types?
Back
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