2nd assessment - genes Flashcards
What is a gamete?
The scientific term for a sex cell (e.g. an egg or sperm cell)
What is a polymer
A substance which is made of many repeating units, e.g. DNA is one as it is made up of many repeating nucleotides.
What is variation?
The differences between members of the same species
What is a chromosome
A long, coiled up molecule of DNA
What is an allele?
A different version of the same gene
What is a genome?
All of the genetic material within an organism
What is a double helix?
The characteristic shape of DNA in which two strands are cooled around each other.
What is a nucleotide?
Consists of a sugar, a phosphate and a base. Many of these join up to form a polymer of DNA.
What is meiosis?
A type of cell division in which 4 genetically gametes are produced . This is important for sexual reproduction.
What is mutation?
A change in the base sequence of DNA. Can lead to different phenotypes in some cases.
What is the human genome project?
A project whose aim was to find every single gene in the human genome.
What is a dominant allele?
An allele which is always expressed in the phenotype if the organism is heterozygous (normally shown with a capital letter)
What is a recessive allele?
An allele which is not expressed in the phenotype if the organism is heterozygous (normally shown with a lower case letter)
What is a carrier?
The term for someone who has a disease causing recessive allele which is not expressed in the phenotype.
What is a gene?
A sequence of DNA which codes for a particular protein.
What does homozygous mean
Having two of the same allele, e.g. two dominant or two recessive alleles.
What does Heterozygous mean
Having two different alleles, one dominant and one recessive.
What is a genotype?
The term for the genes within an organism.
What is a phenotype?
The term for the physical characteristic caused by a genotype.
What is complementary base pairing
This describes how the bases in DNA pair up, e.g. A-T and C-G
What is a haploid?
The term for a cell which carries half of the genetic material in an organism.
What is a diploid?
The term for a cell which carries all of the genetic material in an organism.
What is genetic variation?
A type of variation which is caused by the genes in an organism.
What is environmental variation?
A type of variation which is caused by the environment which an organism is exposed to.
What is a family pedigree?
A way of displaying a family tree of people with genetic disorders to work out probability of inheriting one.
What is a zygote?
A fertilised egg cell.
What is an embryo?
When a zygote has undergone mitosis to form a ball of cells (normally 8).
Describe the process of meiosis is.
Interphase (DNA copied) -> prophase -> metaphase -> anaphase -> telophase -> split into 2 cells -> split again to make 4 genetically different .
Where does meiosis occur?
Plants and animals
What is the function of meiosis?
To make gametes (sex cells).
How many cells does meiosis produce?
4 genetically different daughter cells.
Where in the body does meiosis occur?
Reproductive organs
What type of reproduction is meiosis?
Sexual
Is meiosis diploid or haploid?
Haploid
What do DNA molecules carry?
The code to make proteins that give us our eye colour, hair colour, etc.
What are the 4 chemical bases, and what are there complementary base pairing?
Tigers (T) - Are (A)
Great (G) - Cats (C)
What do the dots in between the bases called?
Weak hydrogen bonds.
What are the strips behind the bases called?
Sugar phrosphate backbone
What are the building blocks of DNA?
- DNA is made of lots of repeating similar units called nucleotides
- Each nucleotide is made of one sugar molecule called deoxyribose, one phosphate group, and one base.
What is in the nucleus of the cell?
Chromosomes
What are chromosomes made up of?
Genes
What chemical are genes made from?
DNA
What are the instructions for making the cell/telling it what to do called?
The genetic code.
What does the dna tell the cell to do?
Make proteins.
What protein controls the level of glucose in the blood?
Insulin.
What do enzymes do?
They are an important group of proteins that control all chemical reactions in cells.
What are the repeating units in dna called?
Nucleotide
What gives the DNA strength?
Hydrogen bonds
What is the phenotype of bob if he’s the genotype Bb. (B = brown)
Brown
What are the two gamete that fuse to create a fertilised egg cell?
Pollen and ova (eggs)
If bob has the genotype Bb, what is his phenotype?
Brown
What are the names of the two gametes that fuse to create a fertilised egg cell?
Pollen and ova (eggs).
What genotype do females have?
XX
What genotype do males have?
Xy
What is cystic fibrosis?
- an inherited disease cause by a RECESSIVE allele.
- carriers of the disease (Cc) aren’t affected.
- only homozygous recessive individuals (CC) develop the disease.
What was the aim of the human genome project?
- to work out the order of all the three billion base pairs in the human genome.
- to identify all the genes and what these genes code for.
What are the advantages of the human genome project?
- breast cancer screening: faulty gene can be identified
- new knowledge of how humans have evolved
- personalised medication/treatment.
- gene therapy: cystic fibrosis patients can correct their faulty genes.
What are the disadvantages of the human genome project?
- 3 billion pounds were spent on HGP -> waste of money
- could lead to discrimination -> if genomes are accessible to all, employers may deny you a job if you have a faulty gene.
What is discontinuous variation?
Where the data can only take a limited set of values. Controlled by genes only - plotted as a bar-chart. E.g. blood group.
What is continuous variation?
Where the data can be any value in a range. Controlled by a combination of genes and environment plot as histogram. E.g. height.
Describe a discontinue variation graph.
- variation in number of whole values is discontinuous as you can only have whole numbers, not values in between.
- when drawing a frequency bar chart, leave a gap between bars to make the discontinuity obvious.
Describe a continuous variation graph.
- The chart is drawn with no gaps between bars, to show that the data are continuous
- values are grouped to make it easier to see patterns in data
- Leaf length is a continuous variable as it can be any value within the range.
Describe a continuous variation graph where the results look like a triangle.
- normal distribution curve
- continuous variation/data
- a correct interpretation of the data - mean, mode, and so on.
