Inheritance Flashcards
what is sexual reproduction? (3)
- the fusion of male and female gametes
- the offspring receives genetic information from both the male and female parents
- every gamete is different, which means there’s variation in the offspring
what is asexual reproduction? (3)
- only one parent is involved so there’s no fusion of gametes and no mixing of genetic information
- all offspring are genetically identical because all the gametes are the same
- only involves mitosis
where does meiosis take place?
in the reproductive organs
what is the meiosis process? (3)
-
dna replication
- the cell duplicates its genetic information, forming ‘two-armed’ chromosomes
- each ‘arm’ is an exact copy of the other
-after replication the chromosomes arrange themselves into pairs -
first division
- the chromosomes line up in the centre of the cell
- they are then pulled apart so each new cell has only one copy of each chromosome -
second division
- chromosomes line up again in the centre of the cell, where the two ‘arms’ are pulled apart
what is the end product of meiosis?
four non-identical daughter cells are produced and the chromosomes in these cells are now single - at the beginning, they were in pairs
what happens after fertilisation?
the new cell divides by mitosis, producing a clump of identical cells (an embryo)
what is DNA? (3)
- contained within chromosomes
- determines our inherited features
- consists of two strands
what is the name of the structure of DNA?
double-helix structure
define gene
a small section of DNA on a chromosome
what does each gene do?
encodes for a specific sequence of amino acids to make a specific protein
define genome
the entire genetic material of an organism
define human genome
the entire genetic material that makes a human
what are the benefits of scientists studying the entire human genome? (3)
- helps us to search for genes that are linked to certain diseases
- helps us to understand and treat inherited disorders
- can use the human genome to trace human migration patterns
define allele
versions of a gene
define genotype
tells us the allele’s present
define phenotype
tells us the characteristics/features of a person based on their alleles
define homozygous
a person that has two copies of the same allele
define heterozygous
a person that has two different allele’s
in which case would a recessive allele be shown in the phenotype of a person?
if there’s two of them (ee, ff, cc)
what is cystic fibrosis
a disorder of cell membranes
which allele’s must a person have in order to have cystic fibrosis?
two copies of the defective cell membrane allele (cc)
which allele’s must a person have to count as a carrier of cystic fibrosis?
one defective allele and one normal allele (Cc)
what is polydactyly
extra fingers or toes
what is polydactyly caused by?
a dominant allele
define embryo screening
in which an embryo is tested to see if they have the allele’s for inherited disorders
what is the advantage and disadvantages (2) of embryo screening?
ADVANTAGE
scientists may be able to correct faulty allele’s and use this to treat inherited disorders
DISADVANTAGES
expensive - people believe the money should be spent elsewhere in the health service
unethical - some healthy embryos are destroyed; there’s a possibility that in the future we may be able to produce offspring with desire-able features through screening
