Topic 6 (Inheritance, Variation And Evolution) Flashcards
What are chromosomes
Chromosomes are long molecules made up of DNA
What is DNA
DNA stands for deoxyribonucleic acid, it is a chemical that all genetic material in a cell is made of
What is a gene
A gene is a small section of DNA found on a chromosome
What do genes do
Each gene codes for a particular sequence of amino acids which are put together to make a specific protein
What is a genome
A genome is a fern for the entire set of genetic material in an organism
DNA is made up of repeating units called nucleotides. What is a nucleotide
A nucleotide consists of a sugar, aphosphate group and one base. One of four different bases joins to the sugar and the sugar joins to the phosphate.
What are the bases that join to nucleotides
A,T,C and G
A always pairs up with T
C always pairs up with G
What are ribosomes and what do they do
Ribosomes are tiny structures that make proteins, they make proteins using the code in the DNA.
How do the ribosomes get the code to make proteins
•DNA can not get out of the nucleus but the ribosomes are in the cell membrane
•The cell needs to get the code from the DNA to the ribosome
•This is done using mRNA which is made by copying the code from the DNA and acts as a messenger from DNA to ribosome
What are mutations
Mutations are changes to the genetic code.
What is the problem with mutations
Mutations can have very little or no effect however some mutations can have a serious effect on a protein. Sometimes the mutation may code for an altered protein with a change in its shape, this could effect its ability to function and cause serious problems for the person
There are three types of mutation, what are they
•Insertion-Adding a random base to the code
•Deletion-Removing a random base from the code
•Substitution-When a base is replaced by another base
How does sexual reproduction work
•The mother and father produce gametes by meiosis
•Each gamete contains 23 chromosomes, half the amount of a normal human body cell
•The gametes fuse together to form a full cell with the full 46 chromosomes
•This is why the offspring inherits characteristics from both parents
What is sexual reproduction
The fusion of male and female gametes, to create offspring with a mixture of their parents genetic information
What is asexual reproduction
Asexual reproduction happens by mitosis, an ordinary cell makes a new cell by dividing into two
What is meiosis
Meiosis
•Before cell starts to divide, it duplicates its genetic information, forming two armed chromosomes
•In the first division in meiosis the chromosome pairs line up down the middle, they are then pulled apart so each new cell has one copy of each chromosome
•In the second division, the chromosomes line up down the middle again, they are pulled apart leaving each of the four gametes with only a single set of chromosomes in it
•Each gamete is genetically different as the chromosomes are shuffled up during meiosis
What are the advantages of sexual reproduction
•Variation in offspring
•Survival advantage
•Natural Selection
What are the advantages of asexual reproduction
•Only one parent needed
•Less energy required
•Faster
•Identical offspring in favourable conditions
What is the 23rd pair of chromosomes known as
XX or XY, these chromosomes decide your sex
If you have XX chromosomes what is your sex
Female
If you have XY chromosomes what sex are you
Male
What is Hetrozygous
One dominant allele one recessive allele
What is homozygous dominant
Two dominant alleles
What is homozygous recessive
Two recessive alleles
