Cell Division and Inheritance Flashcards
Name the functions of the nucleus
- Control cellular structure
- Directs cellular activities
- Produces ribosomes
Name the common features of a cellular structure
Cell membrane Nucleus DNA/genetic material endoplasmic reticulum Cytoplasm Mitochondria Gogli apparatus Ribosomes
Define the term alleles
Alternative versions of a gene
Define the term homozygous alleles
Have identical information for a trait
Define the term heterozygous alleles
Have different information for a trait
What are the two types of cell division?
- Somatic
- Reproductive
Describe Somatic cell division
Aim to replicate cells to replace dead or injured cells or add new cells during tissue growth (Occurs through mitosis and cytokinesis)
Describe reproductive cell division
Aim to produce the gamete cells (Sperm & oocyte) required for the next generation (Occurs through meiosis)
For somatic cell division, include the end products, the number of chromosomes in each new cell, the location of where the cell division occurs and the type of division that occurs
- The end result is 2 daughter cells
- 46 chromosomes (23 pairs)
- Occurs all the cells of the body except for the germ line
- Mitosis (Genetically identical)
For reproductive cell division, include the end products, the number of chromosomes in each new cell, the location of where the cell division occurs and the type of division that occurs
- The end result is four daughter cells called haploid cells
- Contains 23 chromosomes
- Occurs in the gonads, In males, it occurs in the testes and in females it occurs in the ovaries
- Meiosis (Genetically variable)
What are the three main stages of somatic cell division?
- Interphase
- Mitosis
- Cytokinesis
What are the cell processes through interphase include?
- Metabolism (Cellular respiration, protein synthesis)
- Duplication (replication) of chromosomes
- Cell growth (protein synthesis)
- Production of more organelles in preparation for cell division
Explain how genetic variation occurs
Crossing over increases genetic variation which occurs during meiosis 1 and it is the exchange of genes between homologous (paired) chromosomes
Define cancer
Group of diseases that results from uncontrolled or abnormal cell proliferation (to grow by rapid production). Uncontrolled cell division results in excess tissue called a tumour (or neoplasm)
Define Malignant tumours and Benign tumours
- Malignant tumours undergo metastases (The spread of cancerous cells to other part of the body)
- Benign tumours do not metastasise (Not cancerous, They do not spread)
What type of cancer arises from epithelial tissue?
Carcinoma
What type of cancer arises from Melanocytes?
Melanoma
What type of cancer arises from lymphatic tissue?
Lymphoma
What type of cancer arises from leukocytes?
Leukaemia
What is the process of Interphase?
- Replication of DNA
- Duplication of chromosomes
- Metabolism (eg cellular respiration, protein synthesis
Production of more organelles)
How is interphase reached?
- Cell grows, replicates the DNA and prepares for mitosis
- 2 complete and identical DNA molecules produced.
What are the 4 stages of mitosis?
- Prophase
- Metaphase
- Anaphase
- Telophase
What is mitosis?
- The four stages result in the division of the nucleus.
- Process where a single cell divides into two identical daughter cells (cell division)
State three causes of cancer
- Environmental agents (Chemical and radiation)
- These chemicals or radiation are called carcinogens
and include:
□ Cigarette Tar, radon gas, UV light
- These chemicals or radiation are called carcinogens
- Viruses
- Eg. HPV causes cervical cancer by stimulating
abnormal proliferation of cells - Genes
- Abnormalities of the genes that control and
regulate cell division
Explain the difference between Meiosis 1 and Meiosis 2
Meiosis I begins with one diploid parent cell and ends with two haploid daughter cells, halving the number of chromosomes in each cell. Meiosis II starts with two haploid parent cells and ends with four haploid daughter cells, maintaining the number of chromosomes in each cell.
Define Inheritance
Is the passage of hereditary traits from one generation to another
Define Genetics
Is the branch of biology that deals with inheritance
Define genotype
Is the genetic makeup of an individual
Define phenotype
Is the physical characteristics determined by the genotype and the environment
Define mutation
Is a permanent, heritable change in a gene that causes it to have a different effect than it had previously
Define autosomes
Are any chromosomes which aren’t sex chromosomes
Define x-linked
Is a trait where a gene is located on the X chromosome
What is a dominant allele?
Allele that is always expressed or evident in a person. It does this by over-riding the influence of the corresponding allele on the other homologous chromosome (eg. Pp)
What is a recessive allele?
allele that is completely hidden or masked by the presence of a dominant allele. A recessive allele is only expressed when no dominant allele is present (eg. pp)
Explain Autosomal dominant and give an example
Caused by a mutation of a single gene on a chromosome (for example, Huntington’s disease) One heterozygous parent will have a 50% chance of having a child with the disease
Explain Autosomal recessive and give an example
Caused by mutations of two gene pairs on a chromosome (for example cystic fibrosis)
Explain X-linked recessive and give an example
Caused by mutation on the X chromosome (for example Haemophilia or colour blindness) This is more common in men as have only one X chromosome
Define multiple allele inheritance
Where some genes have more than two alternate forms (eg. Allele coding for blood type) - 6 possible genotypes produce 4 blood types (phenotypes)
Define complex inheritance and give one example of a genetic trait carried by this type of inheritance
- Traits that have a genetic component that does not follow strict Mendelian inheritance. May involve the interaction of two or more genes or gene-environment interactions.
- Examples include:
- Skin and hair colour (affected by sun exposure,
nutrition)- Height (affected by malnutrition or disease)
- Skin and hair colour (affected by sun exposure,
Describe the difference between autosomes & sex chromosomes
- Autosomes are any chromosomes other than a sex chromosome - they are the 22 out of 23 pairs of chromosomes
- Sex chromosomes are the 23rd pair that determine whether an individual is male or female. In females, the 23rd pair consists of XX, in males it consists of XY
Explain why many x-linked conditions primarily affect males
Because there are no counterbalancing dominant genes on the Y-chromosome
Give two examples of x-linked (sex-linked) conditions
- Red-green colour blindness
- Lack of either red or green cones, so seen as
same colour
- Lack of either red or green cones, so seen as
- Haemophilia
- Sex-linked trait where blood fails to clot
Explain the terms trisomy & monosomy
A trisomy is a chromosomal condition characterised by an additional chromosome.
Monosomy is used to describe the absence of one member of a pair of chromosomes.
Give an example of Trisomy
Down syndrome for example, they have an extra 21st chromosome
Give an example of monosomy
Turner syndrome for example which affects girls. The cause of Turner syndrome is a completely or partially missing X chromosome
Somatic cell division results in what?
2 genetically identical cells
When the alleles of a gene pair are different they are said to be what?
Heterozygous
The end result of Meiosis is the production of cells that have how many chromosomes?
23 chromosomes
The gene for tongue rolling is dominant. If the father is heterozygous and the mother is homozygous dominant the probability that their child will be a tongue roller is…
100%
Haemophilia is a sex-linked recessive condition. If a man with haemophilia has children with a heterozygous woman, the possible outcomes are…
One potential male and one potential female will have Haemophilia