Inheritance Flashcards
How many chromosomes does the average human body cell contain?
46
Or 23 pairs
How many chromosomes does the average human gamete contain?
23
Mitosis
Splitting of human body cells into 2 genetically identical daughter cells
Why does mitosis occur?
For growth, repair and development of tissue
Meiosis
Splitting of gametes to make 4 genetically different daughter cells
Where does meiosis take place
Reproductive organs
Testes/ovaries
Chromosome
Long threads that contain the molecule DNA
How are chromosomes in a diploid cell?
Each normal human body cell has 23 chromosomes
And also a copy of that cell
1 copy from the mother
And another from the father
So 46 in total
How are chromosomes in a haploid cell?
Only 23 chromosomes with no copies from parents
As they are a mix of parents dna to form your own
Because haploid cells = gametes
What is the structure of DNA called?
Double helix
Gene
Small section of DNA in a chromosome
How do genes work?
They have amino acids
That encode for a specific sequence to make a specific protein that determines an inherited characteristic
Stages of meiosis
Diploid cell in reproductive organs
Replicates copies of chromosomes
The DNA sections get swapped = variation
Divide once
Divide again = 4 different gametes
What happens in fertilisation
The sperm and egg with 23 chromosomes each combine
So makes a diploid cell with 23 pairs or 46 in total
So a pair has one chromosome from the mother and the other from the father
What happens after fertilisation?
Fertilised cell divides by MITOSIS
and creates a clump of identical cells = embryo
The cells then differentiate into different types of cells eg muscle and nerve cells
What are the contents of the double helix?
2 strands which are polymers
Joined together by small molecules
And wrapped around each other
Chromosome pairs
1 from the mother and the other for the father
Contain 2 copies of every gene therefore codes for the same characteristic
Genome
Entire genetic material of an organism
Benefits of studying human genome
Can search for genes linked to inherited diseases
Understand and treat hereditary diseases
Trace human migration patterns from the past / discover ancestry
What are the molecules DNA is a polymer of?
Nucleotides
What are nucleotides made of?
Phosphate group (circle)
Sugar molecule (pentagon)
Base (rectangle)
What changes and stays the same in nucleotides?
Phosphate (circle) and sugar ALWAYS STAY THE SAME
however the base molecule has 4 different types
4 different types of base molecules
A, C, G, T
What are the different nucleotides DNA contains?
Phosphate + sugar + A
Phosphate + sugar + C
Phosphate + sugar + G
Phosphate + sugar + T
How do strands of DNA look in terms of nucleotides?
Phosphates on the outside
Then sugars
And the base facing inside
This is mirrored for the 2nd strand
There are many rows of these