B13 - Reproduction Flashcards
What are gametes?
Sex cells where they’re chromosomes are not paired. (They have 23 not 46)
What are the gametes for humans?
Sperm cells and egg cells
How are gametes made?
By meiosis
What are the gametes in plants?
Pollen and egg cells
Which sex chromosomes do woman have and which ones do men have?
Women have XX chromosomes
Men have XY chromsomes
What type of reproduction do animals and plants go under?
Sexual reproduction
Why is DNA called a polymer?
Its made up of lots of identical units (called nucleotides) joined together
What type of structure does DNA have?
A double helix structure
What is a gene?
A small section of DNA that codes for a specific type of protein
What is a gene in simple terms?
A small segment of a chromosome
What is a genome?
The entire set of genetic material in an organism
What can you do with genomes?
Trace the migration of our ancestors
Identify genes that cause or inherit disease
What are alleles?
Different versions of the same gene that codes for a different version of a characteristic
What does homozygous mean?
Same alleles
What does heterozygous mean?
Different alleles
What does heterozygous mean?
Different alleles
What does genotype mean?
The allele pair for each characteristic
(The alleles broken down from the phenotypes)
What is the phenotype?
The physical expression of the allele pair
(Straight hair)
What allele is shown with a capital letter
The dominant allele
What allele is shown as a lowercase letter?
A Recessive allele
What type of allele is this: RR
Dominant
What type of allele is this: Rr
Dominant
What type of allele is this: rr
Recessive
What method do we use to find out the gene a child might have?
A Punett Square
RR x RR
Dominant
100% R
Rr x Rr
Offspring:
75% R
25% r
3:1
Rr x rr
Offspring:
50% R
50% r
1:1
rr x rr
Offspring
100% r
What is a chromosome?
A structure found inside the nucleus of a cell
What is a chromosome made up of?
Proteins and DNA organized into genes
How many pairs of chromosones are in each cell for humans?
23 pairs (2 in each)
What is the total amount of chromosones a human has?
46 (23 pairs of 2)
What does the nucleus contain?
DNA
What does reproduction mean?
the ability to make members of a species called ‘offspring’
Which 2 ways can reproduction be achieved
Sexually and Asexually
What is a genetic disorder?
A disease caused by a faulty gene or chromosone
What is a recessive genetic disorder?
where the individual has inherited 2 faulty alleles, one from Mum and one from Dad
What is a dominant genetic disorder?
where the individual has inherited ONE faulty alleles. Either from Mum or Dad.
What is cyctic fibrosis?
An inherited disease that affect the lungs and the digestive system. REDO
How do you get cystic firbrosis?
You would of had to inherit two recessive alleles of cystic fibrosis
Examples of genetically inherited disorders
Cystic fibrosis
Haemophilia
Polydactyly
Which allele is cystic fibrosis caused by?
The recessive allele
How many copies do you need to get cistic fibtosis?
Two copies of the allele to have the disorder
If a person has one copy of the dominant allele and one copy of ghe recessive allele, they are called a ………….
Carrier
Bossman fell over when he was young and now has a scar on his arm. What type of variation is this?
Environmental vaeiation
Raj’s blood group is AB. Was this genetically or environmentally inherited?
Genetically inherited
What is the chemical that all genetic material is made up of?
DNA
What does each gene in DNA code for specifically?
Codes for a specific sequence of amino acids which make a specific protein
How many amino acids are used to code for a specific protein?
Only 20
DNA strands are polymers made up of lots of repeating units. What are these units (monomers) called?
Nucleotides
What does each nucleotide consist of?
A sugar, a phosphate group and one base
What do the sugar and phosphate groups in rhe nucleotides form?
A backbone for the DNA strands
What are the pairs in a complementary bade pairing?
A always pairs with T
C always pairs with G
What is each group of bases called!
A triplet
What is a genetic code?
A sequence of bases
What does a triplet code for?
A specific amino acid
Because each protein is made from a different sequence of amino acids, what would this mean?
Each would have a unique shape and carry out a particular function
What are the main uses of proteins?
Enzymes as biological catalysts
Hormones that send messages around the body
Structural proteins that strengthen cells
What is simple definition of protein synthesis?
The process of making proteins
What are the two steps of protein synthesis?
Transcription and translation
What is transcription (the first step of protein synthesis) ?
The process of taking a single gene of DNA and copying it into a structure called mRNA
What is translation (the second step of protein synthesis) ?
The process of taking the mRNA strand (from transcription) and using it to produce a protein
To make a particular protein, what does the specific sequence of bases need to be read by?
Ribosomes
A specific sequence of bases need to be read by ribosomes in order to make a particular protein. How does this happen?
Since the Ribosomes are outside the nucleus, a copy of the gene is made so that it can be small enough to leave the nucleus.
This copy is called mRNA
What are 3 differences between DNA and mRNA?
mRNA is much shorter than DNA
mRNA is only a single strand unlike how DNA is a double strand
Instead of containing the base ‘thymine’, mRNA contains ‘uracil’
What is a mutation? (B13)
A change in the DNA base sequence
For example TAC –> TAG
How often does mutation in DNA occur?
Spontaneously in our cells all the time
What are two things that increase the risk of mutation? (BUT NOT CAUSE)
Carcinogens - harmful chemicals in cigarette smoke
Radiation - like x-rays and gamma rahs
What are the three specific types of mutation?
Substiutions
Insertions
Deletions
What is polyactyly?
An inherited disorder where a baby is born with extra fingers or toes
What is polydactyly caused by?
A dominant allele
What is cystic fibrosis?
An inherited disorder causing overproduction of thick sticky mucus which leads to breathing and digestive problems
