Inheritance Flashcards
What is inheritance?
Inheritance is the transmission of genetic information from generation to generation
Where are chromosomes located?
Chromosomes are located in the nucleus of cells
What are chromosomes?
They are thread-like structures of DNA, carrying genetic information in the form of genes
What is a gene?
A gene is a short length of DNA found on a chromosome that codes for a specific protein (characteristic)
What is an example of a gene?
This could be a structural protein such as collagen found in skin cells, an enzyme or a hormone
What do genes control?
Genes control our characteristics
How do genes control our characteristics?
they code for proteins that play important roles in what our cells do
What is an allele?
Alleles are different versions of a particular gene
How many DIFFERENT chromosomes do humans have?
All humans have 23 different chromosomes in each cell
How many chromosomes do people have in general?
In most body cells, we have 2 copies of each chromosome, leading to a total of 46 chromosomes
What cells are an exception to having 46 chromosomes? How many do they have?
The gametes (egg and sperm cells) only have one copy of each chromosome, meaning they have a total of 23 chromosomes in each cell
What does it mean if a cell has a DIPLOID NUCLEI?
Nuclei with two sets of chromosomes are known as diploid nuclei
What does it mean if a cell has a HAPLOID NUCLEI?
Nuclei with one set of unpaired chromosomes are known as haploid nuclei
What is sex determined by?
Sex is determined by an entire chromosome pair (as opposed to most other characteristics that are just determined by one or a number of genes)
What sex chromosomes do females have?
XX
What sex chromosomes do males have?
XY
Who is responsible for determining the sex of the child?
As only a father can pass on a Y chromosome, he is responsible for determining the sex of the child
How can you show the inheritance of sex?
The inheritance of sex can be shown using a genetic diagram (known as a Punnett square)
What is different between a genetic diagram for sex inheritance and inheritance of other features?
the X and Y chromosomes taking the place of the alleles usually written in the boxes
What happens before a cell divides?
When cells divide their chromosomes double beforehand
Why do the chromosomes in a cell double before cell division?
This ensures that when the cell splits in two, each new cell still has two copies of each chromosome (is still diploid)
When is mitosis used?
This type of cell division is used for growth, repair of damaged tissues, replacement of cells and asexual reproduction
What is the definition of mitosis?
Mitosis is defined as nuclear division giving rise to genetically identical cells
- What is the first step to prepare for mitosis?
Just before mitosis, each chromosome in the nucleus copies itself exactly (forms x – shaped chromosomes)