Human Genetics Flashcards
(20 cards)
What is the positive factors of sexual reproduction?
-species will have genetic variation meaning the organism can easily adapt and change in the environment
-genetic variation also means there is more chance of a beneficial mutation that will help the species survive in different situations
What is the negative factors of sexual reproduction?
-takes a long time (e.g: human pregnancy lasts 9 months
-Must find a mate in order to reproduce (this may be an issue for endangered species as it can be harder to find mate if there are limited options left
What are the key differences between Mitosis and Meiosis?
MITOSIS
-both genetically identical cells
-produces 2 daughter cells
-produces diploid cells (full set of chromosomes 46)
MEIOSIS
-all cells have genetic variation meaning they’re all genetically different
-produces 4 daughter gametes
-haploid cells (have half the genetic information so when male and female gametes fuse together they have a full set)
What are the 5 steps of Meiosis?
-DNA replication(makes double) so there is enough for each cell
-Chromosomes line up in pairs in the centre of cell (one chromosome will come from the father, the other from the mother)
-The pairs are pulled apart so that each new cell has one copy of each chromosome (some from mum, some from dad)
-In the second division, the chromosome line up in the centre of the cell again and the chromatids (arms of chromosomes) are pulled apart
-You get 4 haploid daughter cells (gametes) each gamete had a single set of chromosomes and are genetically different
What is the shape of DNA?
Double Helix
DNA is a giant polymer. What does this mean?
It means it’s a long molecule made of repeating nucleotides
What do nucleotides consist of?
-a phosphate
-a base
-a sugar
What are the four different types of bases?
-Thymine
-Adenine
-Cytosine
-Guanine
What are the base parings?
A always with T
C always with G
How are the base pairing joined together?
Via weak hydrogen bonds
What is a gene?
A section of DNA?
What is an allele?
Different version of a gene
(You have two alleles for every gene in your body, one from mum, one from dad)
What does Homozygous mean?
The same two alleles (e.g: blue eyes from both mum and dad)
What does Heterozygous mean?
Different alleles (blue eyes from mum and brown eyes from dad)
Alleles can be either….?
Dominant or recessive
What does a dominant allele mean?
Overrides recessive and is the most powerful trait (shown by capital letter B)
What is the recessive allele?
Weaker than dominant ( ptedented using lower case letter
What is a Genotype?
They are all the different alleles in your entire DNA
What is a phenotype?
Only the alleles that outwardly show
How can environment play a part in stunting your potential?
E.g: if you have tall genes but a lack of food/ sleep you might not ever reach your full potential height
