Life Line (Biology) Flashcards
Which base is always linked to cytosine
Guanine
Which base is always linked to adenine
Thymine
What does complementary base pairing mean
Each member of a base pair is complementary to its partner
What is a double helix
The two polynucleotide chains wind around each other to form a double helix, with the bases on the inside and the sugar- phosphate backbones on the outside
What is cell division
Cell division is a two- stage process. There is a division of the nucleus (called mitosis) followed closely by a division of the cytoplasm in which the whole cell splits into two daughter cells. During nuclear division the DNA molecules making up the chromosomes accurately reproduce themselves before being shared out equally between the daughter cells. This process, called DNA replication.
What are the 6 stages of DNA replication
- DNA molecule unwinds/untwists
- The DNA molecule unzips
- Free nucleotides pair up with their complementary partners.
- New hydrogen bonds form between the bases
- Strong sugar phosphate bonds form between the nucleotides
- Two identical daughter DNA molecules form.
What are the differences between DNA and RNA
Number of nucleotide strands present in one molecule of nucleic acid = RNA - 1 DNA - 2
Complementary base partner of A = RNA - uracil DNA - thymine
Sugar present in nucleotide structure = RNA - ribose DNA - deoxyribose
What are the 4 types of bases of DNA
A = adenine T = thymine G = guanine C = cytosine
What is protein synthesis
DNA is protected in the nucleus at all times and yet protein synthesis occurs in the cell cytoplasm. A copy of the gene for the required protein is made and transported to the cytoplasm here it’s genetic code is read and the protein built up from amino acids. This ‘go-between’ molecule is called messenger RNA (mRNA)
What is mRNA
The completed molecule of mRNA leaves the nucleus through a pore in the nuclear membrane and enters the cytoplasm. Each triplet of bases on mRNA is called a codon
What’s tRNA
A second type of RNA is found in the cells cytoplasm. This is called transfer RNA (tRNA). Each molecule of tRNA has only one of its Triplets of bases exposed. This triplet, known as anticodon, corresponds to a particular amino acid. Each tRNA molecule picks up the appropriate amino acid from the cytoplasm at its site of attachment
What is the lock and key mechanism of the enzyme action
The substrate (key) goes into the enzyme (lock), the enzyme stays the same, but the substrate becomes two different products
Hydrogen peroxide -> O + H2O
(H2 O2) Catalase
Substrate. Enzyme. Products
What does HP COW mean
Hydrogen Peroxide -> Catalase -> Oxygen + Water
What is the first stage of cell division (mitosis)
Nucleus contains long uncoiled chromosomes each doubling to form 2 identical chromatids
What is the second stage of cell division (mitosis)
Short coiled up chromosome (made of 2 chromatids)
What is the third stage of cell division (mitosis)
Chromosome attach at the equator and have spindle fibres attaching to them
What is the forth stage of cell division (mitosis)
The pair of identical chromatids are depressed and moving opposite directions (poles)
What is the 5th stage of cell division (mitosis)
The separated chromatids (now called chromosomes) have a nuclear membrane surrounding them and the cytoplasm divides
What is the 6th stage of cell division (mitosis)
There are now two identical daughter cells with the same amount of chromosomes as the original cell
Describe the maintenance of chromosome complement
Chromosomes provide the main source of genetic information typical of a particular species of living things. It is essential that each cell formed as a result of mitosis receives a full complement of chromosomes, so that during growth and development the cells of a multicellular organisms will be able to provide the animal or plant with all the characteristics of its species
