Flashcards in Inheritance, variation and evolution (need to add from variation onwards) Deck (90)
What are chromosomes?
long strands of DNA usually found in pairs
What is DNA?
a chemical that all the genetic material of a cell is made up from which contains coded material that determines characteristics
What is a gene?
a small section of DNA found on a chromosome which codes for a particular sequence of amino acids which make a specific protein
What is a genome?
the entire set of genetic material in an organism
Why is understanding the genome important for science and medicine?
-it allows scientists to identify genes linked to different diseases which helps to develop effective treatments for them
-genomes can help to trace migration patterns of populations to help work out when new populations split off and what route they took
What are nucleotides?
repeating units which make up DNA strands (making the strands polymers)
What does one nucleotide consist of?
-one sugar molecule
What is a backbone formed from (in a nucleotide)?
one sugar and one base
What is complementary base pairing?
the idea that base A always pairs up with base T and base C always pairs up with base G
Which bases always pair together?
A and T
C and G
What does the order of bases in a gene determine?
the order of amino acids in a protein
What is mRNA and what does it do?
it is a molecule which carries a code from the DNA to the ribosome so that proteins can be made in the cytoplasm by the ribosomes
Give some examples of proteins
-enzymes (biological catalysts)
-hormones (carry messages around body)
-structural proteins (physically strong)
What are mutations?
random changes to DNA
How do mutations occur?
continuously and randomly
Do mutations have much affect?
they mostly have no effect because they code for the same amino acid so that its function/appearance is unaffected
sometimes they alter the amino acid and therefore the protein so that its shape/function is affected
What are the three types of mutations?
insertion (adding an extra base)
deletions (loosing a base)
substitution (replacing a base)
What is an insertion mutation?
where a new base is inserted into the DNA base sequence where it shouldn't be
What is a deletions mutation?
when a random base is deleted from the DNA base sequence
What is a substitution mutation?
when a random base in the DNA base sequence changes to a different base
What are the two types of reproduction?
What is sexual reproduction?
where genetic information from two organisms (father and mother) is combined to produce offspring which are genetically different to both parents (which has half of its chromosomes from each parent -23 each)
What is asexual reproduction?
reproduction by only one parent which produces a genetically identical offspring (a clone)
What is fertilisation?
the fusing of gametes (eg. egg and sperm) in sexual reproduction to form a cell (fertilised egg) with the full number of chromosomes
What are gametes?
sex cells with half the number of chromosomes as a normal cell
eg. egg and sperm
What is meiosis?
cell division which produces cells with half of the number of normal chromosomes (gametes)
Describe the process of meiosis
-the cell's genetic information duplicates
-in the first division, the chromosome pairs line up in the centre of the cell and the nucleus and cell splits (with half of the chromosomes in each)
-in the second division, the chromosomes line up in the centre of the cell and the arms of the chromosomes get pulled apart
-you get four gametes, each with a single set of chromosomes which are all genetically different to each other
What is the cell cycle?
the cycle where body cells in multicellular organisms divide to produce genetically identical cells
Why does the cell cycle take place?
to grow new cells or replace damaged cells