B2 topic 1 The building blocks of cells Flashcards
List the 4 common organelles found in animal & plant cells.
- Nucleus
- Cytoplasm
- Cell membrane
- Mitochondria
What are all living things made up of?
Cells
What is the function of the nucleus?
Contains genetic material (DNA) , which controls the activities of the cell
What is the function of the cytoplasm?
Jelly-like substance where most of the chemical reactions take place
What is the function of the cell membrane?
Controls the movement of substances into and out of the cell
What is the function of the cell wall?
Gives the cell support and is made of cellulose
What is the function of the vacuole?
illed with cell sap to help keep the cell turgid
What is the function of the chloroplast?
Contain chlorophyll, which absorbs light energy for photosynthesis
What is the function of the mitochondria?
Where most of the reactions for respiration take place, respiration releases energy that the cell needs to work
What features does a bacterial cell have?
- Chromosomal DNA
- Plasmids
- The Flagellum
- Cell Wall
What is a chromosomal DNA?
One long circular chromosome, which controls the cells activities and replication. It floats free in the cytoplasm
what are plasmids?
Small loops of extra DNA that are not part of chromosomal DNA, contain genes for things like drug resistance and can be passed between bacteria
What is the function of the flagellum?
(Plural Flagella) is a long hair like structure that rotates to make bacteria move
How do you calculate magnification?
Length of image
___________
Length of specimen
what is ‘DNA’?
DNA is the molecule that carries instructions for characteristics from the parent to the offspring, it’s a double helix of paired bases
What shape is DNA?
A double helix
What are the 2 strands of DNA held together by?
Chemicals called bases
What are the four bases?
Adenine Thymine Guanine and Cytosine
Which bases pair together?
A&T C&G
What are bases held together by?
Weak hydrogen bonds
What’s a gene?
A section of DNA
What does the sequence of bases in a gene code for?
A specific protein
Who discovered the structure of DNA?
Watson, Crick, Franklin and Wilkins
What did Franklin and Wilkins do?
Worked out DNAs helical structure using x-Ray refraction
What did Watson and Crick do?
They used Franklin and Wilkins ideas and their own know leg to create a model where all of the pieces fitted together
How do cells make proteins?
By stringing amino acids together in a specific order
How many amino acids are used to make all the proteins?
20
What are three bases called?
A triplet or a codon
How are proteins made in a cell?
By organelles called ribosomes
Why can’t DNA move out of the cell nucleus?
Because it’s to big
How does the cell get information from the nucleus to the cytoplasm?
Using mRNA
What is mRNA?
Very similar to DNA, only a single strand, it’s a messenger between DNA in the nucleus and the ribosome
Describe Transcription
2 DNA strands unzip , DNA uses as a template to make mRNA. Base pairing ensures it’s complementary
Describe Translation
mRNA moves out of the nucleus and joins the ribosome in the cytoplasm. Amino acids that match the mRNA code are brought to the ribosome by tRNA. 4) Ribosome sticks amino acids together in a chain to make a polypeptide (protein) this follows the order of the triplet bases (codons) in the mRNA
What 3 things can mutations be?
Harmful, beneficial or neutral
How can a mutation be harmful?
Mutations can cause genetic conditions , for example cystic fibrosis
How can a mutation be beneficial?
It could produce a new beneficial characteristic, for example mutation in genes of bacterial plasmids
How can a mutation be neutral?
Some are nether harmful or beneficial, they don’t effect a proteins function
What’s a mutation?
A change in an organisms DNA base sequence
How could a mutation affect an organisms characteristics?
A mutation could affect the sequence of amino acids in a protein which could affect the shape of the protein and so it’s function. This could in turn affect the characteristics of an individual.
What’s an enzyme?
A catalyst produced by living things
Why do living things produce enzymes?
You can usually increase the speed of a reaction by increasing the temperature but this would also speed up unwanted reactions, so living things produce enzymes to act as biological catalysts as they reduce the need for high temperatures.
What’s a catalyst?
A substance which increases the speed of a reaction without being used up or changed in the reaction.
What ways can enzymes work in and out of cells?
- DNA replication (help copy the DNA)
- Protein synthesis (hold amino acids in place and help form bonds)
- Digestion (digest food molecules)
What do chemical reactions usually involve?
Things being split apart or joined together
What’s a substrate?
The molecule changed in the reaction
What do enzymes have for their substrate?
A high specificity
For the enzyme to work what does the substrate have to do?
Fit into the active site
What is this mechanism called in enzymes?
The lock and key mechanism
State 3 additional organelles found in plant cells.
- Vacuole
- Chloroplasts
- Ridgid cell wall
