Variations And DNA Flashcards
What is the molecule that carries genetic information in cells?
DNA (Deoxyribonucleic Acid)
Where is DNA found in eukaryotic cells?
In the nucleus, within chromosomes
What is the structure that DNA is organized into within the nucleus?
Chromosomes
How many chromosomes do humans typically have?
46 chromosomes (23 pairs)
What is the name of the process where DNA makes a copy of itself?
DNA replication
What are the four nitrogenous bases found in DNA?
Adenine, Thymine, Guanine, Cytosine
What is the complementary base pair for Adenine in DNA?
Thymine
What is the complementary base pair for Guanine in DNA?
Cytosine
What is the name of the process where the genetic information in DNA is used to make proteins?
Protein synthesis (transcription and translation)
What are chromosomes?
Tightly coiled DNA molecules which are found in the nucleus of a cell Chromosomes also carry a large number of genes.
DNA
Is a composed chemical and it contains genetic material found in the nucleus of a cell. !!CONTAINS A CODE FOR AMINO ACIDS!!
Amino acids
Molecules that combine to make proteins
Gene
A section of DNA that codes for a specific protein. Genes tell the cell what order to put the amino acids in.
Allele
Different versions of the same gene
Karyotype
Chromosome map of an organism
What is DNA made up of?
DNA is a polymer made up of many nucleotides.
Why do long strands of DNA twist
To form a double helix
What is a nucleotide
Nucleotides are organic molecules composed of a nitrogenous base, a sugar molecule and a phosphate group.
How does DNA code for a protein
DNA strands consist of 4 different bases, in which 3 bases codes for 1 amino acid, so the bases to join together to form a protein. (Might be asked as a outline how this chain of dna leads to the production of haemogoblin)
How is the helix held together
By hydrogen bases between nitrogenous bases
How do the nitrogenous bases bond
The base in one strand is joined to the base on the opposite strand in the helix
Why are some parts of the DNA that are not coded?
There are parts of the DNA that don’t code for proteins. Since they switch genes on and off so these parts that are not coded control whether a gene is expressed or not, or if a protein was made.
Describe the structure of a nucleotide (4marker)
Phosphates are attached to the sugar molecule, in which 1 of 4 bases are attached to the sugar molecule as well, nucleotides consist of A,T,C,G. The bases (nucleotides) in one strand join the bases in the opposite strand.
Mutation-
An error in the sequence of DNA, occurs during cell division which produces a new allele.
What does a gene do?
Controls different characteristics
Why is DNA described as a polymer
Since it has many nucleotides
How can variation cause differences between individuals/species
Due to the genes they have inherited.
The conditions in which individuals have developed in (e.g. language)
Combination of genes and environment
What are the genetic factors of variation?
Meiosis forms non identical gametes (produces variation)
Fertilization of both egg and sperm (DNA from both parents causes variation)
Mutations (random change in the DNA sequence causes variation)
What are the environmental factors of variation?
Race, ethnicity, nutrition
How characteristics are passed down from
Parents to offspring’s?
Each parent has different alleles for specific traits.
Alleles are passed down into gametes during meiosis.
After fertilization, alleles from both parents unite in the zygote.
Zygote divides into 2 forming identical cells each having a copy of alleles from both parents.
Dominant allele will express.
The father of the twins has brown eyes.
Explain how the characteristic of brown eyes has
been passed from the father to both of his children.
(4 Marks)
The father has the allele for brown eyes. Allele has been passed down into the fathers gamete cell, which has fertilized the egg, then the zygote divides by mitosis forming identical cells, each embryo will have the same alleles as the parents, and the dominant allele which is the fathers, will be expressed on the offspring.
What is an enzyme?
Biological catalysts that speed up the rate of a reaction.
Describe the structure of DNA-
DNA contains a double helix. Contains 4 different bases
Explain how the sequence of bases in a DNA molecule codes for different proteins-
3 bases code for 1 amino acid. The sequence of bases in a DNA molecule determines the sequence of amino acids, and the sequence of amino acids determines which protein is being made
