B13 Flashcards
2 stages of protein synthesis?
Transcription and Translation
3 levels of orginisation in a genome?
- Genes
- DNA
- Chromosones
Advantages of Asexual reproduction?
- Only one parent required
- Requires less energy and time
- Lots of offspring can be produced in a short period
Advantages of Sexual Reproduction?
- Creates genetic variation in offspring
- increasing the probability of species adapting to and surviving enviromental changes
Describe the circumstances in which malarial parasites reproduce sexually and asexually
Malaria parasites reproduce sexually in mosquitoes and asexually in their human hosts
Explain mitosis
1) Cell begins to divide
2) Dna replicates to form two copies of each chromosome
3) Nuclear membrane breaks down. chromosome lines up across centre of the cell
4) one set of chromosome pulled to each end of the cell and nucleus divides
5) cytoplasm and cell membrane divide to two identical cell
Diagram of protein synthesis
draw
Diagram of transcription
draw
Disadvantages of sexual reproduction
- Two parents are required
- More time and energy is required so fewer offspring are produced
effects of a mutation
- enzyme also unchanged so substrate doesn’t fit
- active site shape changed so enzyme doesn’t fir
- active site changed shape so a different substrate fits
Explain how a gene codes for a protein
- A sequence of 3 bases in a gene form a triplet
- Each triplet forms an amino acid
- The order of amino acids determines the structure and function of the protein formed
Features of asexual reproduction
- Involves only one parent
- No joining of special sex cells (gametes)
- No mixing of genetic information
- Gives rise to genetically identical offspring known as clones
Explain how meiosis results in genetic variation within the human species.
Specifically, meiosis creates new combinations of genetic material in each of the four daughter cells. These new combinations result from the exchange of DNA between paired chromosomes.
Give 2 examples of inherited disorders
- Cystic fibrosis
- Polydactyly
How are recessive alleles represented?
Using lower case letters
How can human beings have more than 21,000 different chemicals within them?
The human genome has the ability to make many different proteins from the same gene by using it in different ways or by switching parts of a gene on/off.
How do cells divide in asexual reproduction?
By mitosis
How many chromosomes do gametes have?
23 chromosomes
How many chromosomes do humans have?
46 chromosomes (23 pairs)
How many gametes are made in meiosis?
4
Outline the function of genes
To code for particular sequences of amino acids that produce proteins
Outline the process of translation in protein synthesis
1) mRNA attaches to a ribosome
2) ribosome reads mRNA in triplets. Each triplet codes for one amino acid which is brought to the ribosome by a tRNA molecule
3) A polypeptide chain is formed from the sequence of amino acids which join together
Stages of meiosis
1) chromosome makes identical copies of themselves
2) similar chromosome pair up
3) section of DNA get swapped
4) pairs of chromosome divide
5) chromosome divide
State the full name of the 4 bases found in nucleotides
- thymine T
- adenine A
- guanine G
- cytosine C
Suggest one possible effect of a mutation that changes the shape of a structural protein
The mutation could cause the structural protein to lose its strength
Treatment for cystic fibrosis
Physiotherapy and antibiotics
What are “designer babies”?
A designer baby is a baby whose genetic makeup has been selected or altered, often to include a particular gene or to remove genes associated with disease.
What are alleles?
Different versions of the same gene
What are DNA nucleotides made up of?-
- Commom sugar
- Phosphate group
- Bases
What are the 2 types of reproduction?
Asexual and sexual
What are the carrier molecules called in protein synthesis?
transfer RNA (tRNA)
What are the complementary base pairs found in nucleotides?
t-a
g-c
What are the gametes in plants?
Egg cells and pollen
What are the monomers of DNA?
Nucleotides
What are the risks of genetic screening of embryos?
They can cause a miscarriage
What does a genetic diagram give us?
- the alleles for a characteristic carried by the parents
- the possible gametes that can be formed from these
What does the shape of a protein determine?
Its function
What does the term genotype refer to?
The entire genetic makeup of an individual for a particular characteristic
E.g hair color
What happens when a cell divides by meiosis to form gametes?
The genetic material is copied and then the cell divides into 4 to form 4 genetically different gametes, each with 1 set of chromosomes
What is a carrier?
If a person receives only one recessive allele, their one dominant allele means they do not have symptoms of the disorder. However, they are able to pass it to their children. They are called a carrier.
What is a chromosome?
Chromosomes are thin strands of DNA located in the nucleus
What is a diploid cell?
A cell that has paired chromosomes, one from each parent
What is a dominant allele?
A version of a gene where only one copy is needed for it to be expressed
What is a gamete?
An organism’s reproductive cells also known as sex cells. They consist of (eggs and sperm cells) which have half the number of chromosomes of an individual.
What is a gene?
A small section of DNA on a chromosome that codes for a particular sequence of amino acids, to make a specific protein
What is a genetic cross?
the potential offspring that might result from 2 known parents
What is a heterozygote?
heterozygote = an individual with different alleles for a characteristic
What is a homozygote?
an individual with two identical alleles for a characteristic
What is a mutation?
A change in the genetic material of an organism
What is a recessive allele?
A version of a gene where 2 copies are needed for it to be expressed
What is a zygote?
A fertilised egg cells that results from the union of a female gamete (egg) with a male gamete (sperm)
What is amniocentesis?
A procedure carried out at 15-16 weeks of pregnancy which involves taking some of the fluid from around the developing fetus. This fluid contains fetal cells, which can be used for genetic screening to detect any abnormalities.
What is an inherited disorder?
A disorder caused by inheritance of certain alleles
What is cystic fibrosis?
A disorder of the cell membranes of cells lining the airways and pancreas - causes thick build up of mucus and makes at difficult to eat
What is DNA?
double-stranded polymer of nucleotides, wound to form a double helix
It is essentially the genetic material of the cell
What is gene expression?
specific genes are activated to produce a required protein.
What is meant by a haploid cell?
A cell that only has 23 chromosomes
What is meant by the term genome?
The entire genetic material of an organism
What is meant by the term phenotype?
The visible characteristics of an organism which occur as a result of its genes.
What is meiosis?
Cell division that happens when a diploid cell divides to produce gametes
What is mitosis?
A type of cell division which produces 2 identical daughter cells
What is non-coding DNA?
DNA which doesn’t code for a protein but instead controls gene expression
What is polydactyly?
having extra fingers or toes and is caused by dominant allele
What is protein synthesis?
The formation of a protein from a gene
What is the female sex chromosome?
XX
What is the male sex chromosome?
XY
What is the plant equivalent of mating?
Pollination
What is transcription in protein synthesis?
the information in a strand of DNA is copied into a new molecule of messenger RNA (mRNA).
What is translation?
a protein is synthesized from the information contained in a molecule of messenger RNA (mRNA).
What occurs after translation?
The polypeptide is finally folded into the correct shape and becomes a protein. Peptide bonds form between the adjacent amino acids to finalise the structure.
What type of cell division forms gametes?
Meiosis
What type of reproduction introduces variation?
Sexual reproduction
What was the Human Genome Project?
An international 13 year effort from 1990 to 2003, to discover and map the complete set of human genes
Where are the female and male gametes made?
Female gametes are made in the ovaries
Male gametes are made in the testes
Where does meiosis occur?
Testes of men and ovaries of women
Which base does Uracil replace in mRNA?
Thymine
c
Ethene
Why is meiosis important?
It ensures that all organisms produced via sexual reproduction contain the correct number of chromosomes. Meiosis also produces genetic variation.
Why is understanding the human genome important?
- Searching for genes linked to diseases
- Tracing human migration patterns from the past
- Understanding & treating inherited disorders
Suggest one way embryo screening can help people with a family history
of a genetic disorder?
- Consider if they should get an abortion
- Make them prepared
