Genetics Flashcards
What are the 2 types of reproduction?
Asexual and sexual reproduction
What are the 3 steps of sexual reproduction?
- Mother gamete fuses with father gamete
- Mix genetic info
- Offspring have different combinations of genes from each parent to show a variety of characteristics
What are the advantages and disadvantages of sexual reproduction?
-Offspring are genetically different to parent and each other, so there is the variation; if the environment changes, then some individuals may survive
BUT
-The organism has to find a mate to reproduce which takes time and energy
What are the 3 aspects of asexual reproduction?
- No fusion of gametes; only one parent
- No mixing of genetic info
- All offspring have identical genes to the parent and each other
What are the advantages and disadvantages of asexual reproduction?
-Only one parent; no need to find a mate so is faster
BUT
-All offspring are genetically identical so no variation in population; if the environment changes, all may die
What does asexual reproduction produce?
Clones - identical to the parent
What is meiosis?
A type of cell division that produces 4 daughter cells each with half the amount of chromosomes (haploid number)
What is a gene?
A section of DNA that codes for a particular protein
Describe the stages of meiosis
- Parent cell is diploid
- DNA replication (chromosomes copy themselves and stay attached to each other)
- Cell splits in 2 with each new cell haploid
- Divides in 2 again
- Four daughter cells now haploid
- Mix of genetic info
What is an acronym to help remember the stages of meiosis?
President Donald Cannot Do For Me
What is the genome?
All the DNA of an organism
What are the 4 bases in DNA and what do their pair with?
Adenine with Thymine
Guanine with Cytosine
(They are complementary base pairs)
What is the grouping of a base pair attached to a sugar which is attached to a phosphate group called?
A nucleotide
How many hydrogen bonds form between each base pairs?
C and G = 3
A and T = 2
Why is DNA a polymer?
Because it is made up of several monomers called nucleotides
Describe how DNA is extracted from fruit
- Grind the fruit with sand using a pestle and mortar to separate the cells
- Add detergent to break open the membranes
- Add ice-cold alcohol so that the DNA precipitates out
Why is it important to add detergent to the fruit when breaking open the membranes?
The DNA in the fruit is found in the nucleus which, like the cell, is surrounded by membranes, so to extract the DNA you must break open the membranes by adding detergent
What is a mutation?
Where genetic code has not been transcripted properly
What is the difference between a DNA and a RNA nucleotide?
DNA has deoxyribose sugar whereas RNA has ribose sugar
What is a phenotype?
Observable characteristics - what an organism looks like
What are alleles?
Different forms of a gene
What are the 3 laws that Mendel created for inheritance?
- Each gamete receives only 1 version for a characteristic
- The version of a characteristic that a gamete receives is random
- Some versions of a factor are more powerful than others and always have an effect on the offspring
What does homozygous mean?
The state of having 2 of the same alleles of a particular gene
What is meant by heterozygous?
The state of having 2 different alleles of a particular gene
What is a dominant allele?
The allele that will always have an effect on an organism
What is a recessive allele?
The allele that will only have an effect on an organism’s phenotype when 2 are present
What is the genotype?
The alleles in an organism
What is the likelihood of an event happening, used in genetic diagrams like Punnett squares?
Probability
What is the 3:1 ratio called?
The monohybrid ratio
What is codominance?
When both alleles for a gene affect the phenotype
What are sex-linked genetic disorders?
Disorders that show a different pattern of inheritance in men and women
Why might a person with CF lose body mass?
They produce a lot of mucus that block all the ducts that carry enzymes to the digestive system, meaning less of their food is digested and so there is a less absorption of food; the enzymes work less effectively because of this
What is genetic variation caused by?
The different alleles inherited during sexual reproduction
What are acquired characteristics?
Characteristics that are changed by the environment during the life of the individual
What is discontinuous variation?
Where the data can only take a limited set of values
What is continuous variation?
Where the data can be any value in a range
