Paper 2: Topic 6 Inheritance, variation & evolution - Reproduction (includes DNA & genetics) (LV) Flashcards Preview

Mrs P's GCSE Biology > Paper 2: Topic 6 Inheritance, variation & evolution - Reproduction (includes DNA & genetics) (LV) > Flashcards

Flashcards in Paper 2: Topic 6 Inheritance, variation & evolution - Reproduction (includes DNA & genetics) (LV) Deck (108)
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Name the genetic material found in the nucleus



What does DNA stand for?

Deoxyribonucleic acid


How is the DNA arranged in the nucleus of a eukaryotic cell?

As chromosomes


How is the DNA arranged in a prokaryotic cell?

  • Free in the cytoplasm as a nucleoid
  • And additional pieces of DNA are also found in bacteria in small loops called plasmids


How do chromosomes normally exist in cells?

In pairs


Where do the chromosomes in the nucleus originate (come) from?

One from each pair comes from the maternal ovum and one from each pair comes from the paternal sperm


What type of molecule is DNA?



DNA is a polymer. What are the monomers that are linked other to form DNA called?



Describe the general shape of a DNA molecule

A double helix


Define the term gene

A small section of DNA that codes for the sequence of amino acids that makes a specific protein


How many amino acids exist naturally?



Define the term genome

The entire set of genetic material that exists in a single organism


Why has the study of the Human genome been useful for scientists?


Hint: give 4 reasons

  • They have Identified genes linked to specific diseases
  • Gained an understanding of how some diseases are inherited
  • Used this understanding of inheritance to develop effective treatments
  • Used the genome to determine historical migration patterns of certain groups of people


State the 3 main components of a nucleotide

  1. Phosphate group
  2. Sugar (called deoxyribose)
  3. Base


How many different types of base are found within DNA?



What are the 4 different types of base found in DNA nucleotides?

A, T, C and G


How do the bases pair up in DNA?

  1. A always pairs with T
  2. C always pairs up with G


How do the nucleotide bases code for the production of proteins?

  • 3 bases codes for one amino acid
  • So the sequence of bases codes for the sequence of amino acids that are linked together to make a protein


Some parts of the DNA do not code for specific proteins. What is the role/function of these parts of the chromosome?

  • To control if the genes are expressed
  • Which determines if the proteins are actually produced


Which organelle is responsible for producing proteins?



How are proteins made? Hint: 5 steps

  1. The instructions in the gene are copied into a messenger molecule called mRNA
  2. The mRNA leaves the nucleus and travels to the cytoplasm
  3. Ribosomes attach to the mRNA
  4. Carrier molecules carry amino acids to the ribosome The ribosome joins the amino acids together in the sequence that is determined by the mRNA


After the amino acids are joined together in a long chain, what must happen before the protein can carry out it’s function?

  • When the protein chain is complete it folds up to form a unique shape.
  • This unique shape enables the proteins to do their function


Give 5 different functions of proteins

Hint: think STEAM H

Structural role e.g. collagen (found in blood vessel walls), keratin (found in hair and nails)

Transport role e.g. haemoglobin (carries oxygen around the body)

Enzymes e.g. proteases


Mechanical role e.g. myosin (found in muscle cells to allow muscle cells to contract)

Hormones e.g. insulin


Define the term mutation

  • A change to the sequence of DNA bases
  • This changes the genetic code


Describe how often mutations occur

Continuously, spontaneously and randomly


State the 3 effects of mutations

  1. Neutral
  2. Harmful
  3. Beneficial


State 3 factors that increase the risk of a mutation occurring

  1. Exposure to UV light
  2. Exposure to X-rays
  3. Exposure to certain chemicals e.g. benzene


How does a change in DNA bases cause a change in the protein structure and function?

  • A change in one or more DNA bases will change the triplet sequence of the DNA
  • This will change the sequence of triplets on the mRNA
  • This will change the carrier molecule that brings the amino acids to the ribosome
  • The sequence of amino acids will then change
  • This changes the structure of the protein
  • Which then changes the function of the protein


Suggest how mutations may cause a change in enzyme activity

  • The mutation will cause the amino acids sequence to change
  • This could change the shape of the active site
  • This could prevent the substrate from fitting into the active site
  • This then prevents the formation of enzyme-substrate complexes
  • So the rate of reaction will decrease


Suggest how mutations may cause a change in structural proteins

  • The amino acid sequence in the protein will be changed
  • This changes the shape of the protein
  • This reduces the strength of the structural protein

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